diff --git a/src/models/book.rs b/src/models/book.rs
index e2a33e7..e8a5898 100644
--- a/src/models/book.rs
+++ b/src/models/book.rs
@@ -149,6 +149,18 @@ impl BookOperator {
             .context(DBSnafu)
     }
 
+    /// Finds vec of book by its Owner
+    pub async fn find_all_by_current_holder(
+        &self,
+        current_holder_id: i32,
+    ) -> Result<Vec<Model>, BookError> {
+        Entity::find()
+            .filter(Column::CurrentHolderId.eq(current_holder_id))
+            .all(&self.state.db)
+            .await
+            .context(DBSnafu)
+    }
+
     /// Creates a new book from the given form data.
     pub async fn create(&self, form: BookForm) -> Result<Model, BookError> {
         let book = ActiveModel {
diff --git a/src/models/user.rs b/src/models/user.rs
index 0699e42..bdf2624 100644
--- a/src/models/user.rs
+++ b/src/models/user.rs
@@ -1,4 +1,5 @@
-use crate::models::book::BookOperator;
+use crate::models::book;
+use crate::routes::book::BookForm;
 use crate::routes::user::UserForm;
 use crate::state::AppState;
 use crate::state::error::UserSnafu;
@@ -38,6 +39,8 @@ pub enum UserError {
     DB { source: sea_orm::DbErr },
     #[snafu(display("User with id {id} not found"))]
     NotFound { id: i32 },
+    #[snafu(display("Book error"))]
+    Book { source: super::book::BookError },
 }
 
 #[derive(Debug)]
@@ -90,7 +93,46 @@ impl UserOperator {
         }
     }
 
+    /// Delete user by ID.
+    /// Before deleting the user, you must search for all the books they own in order to delete them beforehand,
+    /// then search for all the books they have borrowed in order to update the current holder to None.
     pub async fn delete(&self, user_id: i32) -> Result<DeleteResult, UserError> {
+        // get all
+        let owner_books = book::BookOperator::new(self.state.clone())
+            .find_all_by_owner(user_id)
+            .await
+            .context(BookSnafu)?;
+
+        // Delete all book with owner_id = current_user
+        for owner_book in owner_books {
+            book::BookOperator::new(self.state.clone())
+                .delete(owner_book.id)
+                .await
+                .context(BookSnafu)?;
+        }
+
+        let current_holder_books = book::BookOperator::new(self.state.clone())
+            .find_all_by_current_holder(user_id)
+            .await
+            .context(BookSnafu)?;
+
+        // Update all book with current Holder = current user
+        for current_holder_book in current_holder_books {
+            let form = BookForm {
+                title: current_holder_book.title,
+                authors: current_holder_book.authors,
+                owner_id: current_holder_book.owner_id,
+                description: current_holder_book.description,
+                comment: current_holder_book.comment,
+                current_holder_id: None,
+            };
+
+            book::BookOperator::new(self.state.clone())
+                .update(current_holder_book.id, form)
+                .await
+                .context(BookSnafu)?;
+        }
+
         let user: Option<Model> = Entity::find_by_id(user_id)
             .one(&self.state.db)
             .await
diff --git a/src/state/error.rs b/src/state/error.rs
index 9a316be..e3b6a39 100644
--- a/src/state/error.rs
+++ b/src/state/error.rs
@@ -5,10 +5,7 @@ use log::error;
 use snafu::prelude::*;
 
 use crate::{
-    models::{
-        book::{BookError, NotFoundSnafu},
-        user::UserError,
-    },
+    models::{book::BookError, user::UserError},
     state::config::ConfigError,
 };
 
diff --git a/templates/base.html b/templates/base.html
index 5e2038d..58b2ef0 100644
--- a/templates/base.html
+++ b/templates/base.html
@@ -28,5 +28,4 @@
   <script src="/assets/js/bootstrap.min.js"></script>
   <script src="/assets/js/script.js"></script>
 </body>
-
 </html>
diff --git a/templates/components/dropdown.html b/templates/components/dropdown.html
index ecd95a7..37dc290 100644
--- a/templates/components/dropdown.html
+++ b/templates/components/dropdown.html
@@ -22,10 +22,29 @@
       {% endif %}
       <li><a class="dropdown-item" href="/{{ sub_path }}/{{ book.id }}/edit">Edit</a></li>
       <li>
-        <form method="post" action="/{{ sub_path }}/{{ book.id }}/delete" class="mb-0">
-          <input class="dropdown-item" type="submit" value="Delete">
-        </form>
+        <a class="dropdown-item" href="#" data-bs-toggle="modal" data-bs-target="#deleteUserModal{{ book.id }}">Delete</a>
       </li>
     </ul>
   </div>
+
+  <!-- Modal -->
+  <div class="modal fade" id="deleteUserModal{{ book.id }}" tabindex="-1" aria-labelledby="deleteUserModal{{ book.id }}Label" aria-hidden="true">
+    <div class="modal-dialog">
+      <div class="modal-content">
+        <div class="modal-header">
+          <h1 class="modal-title fs-5" id="exampleModalLabel">Confirmation</h1>
+          <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button>
+        </div>
+        <div class="modal-body">
+          <p>Are you sure ?</p>
+        </div>
+        <div class="modal-footer">
+          <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
+          <form method="post" action="/{{ sub_path }}/{{ book.id }}/delete" class="m-0">
+            <input class="btn btn-danger" type="submit" value="Delete">
+          </form>
+        </div>
+      </div>
+    </div>
+  </div>
 {% endmacro %}