add delete bookmark context menu command

bot/exts/utilities/bookmark.py

@@ -1,6 +1,5 @@
 import logging
 import random
-from typing import Optional
 
 import discord
 from discord.ext import commands
@@ -73,6 +72,10 @@ def __init__(self, bot: Bot):
             name="Bookmark",
             callback=self._bookmark_context_menu_callback,
         )
+        self.delete_book_mark_context_menu = discord.app_commands.ContextMenu(
+            name="Delete bookmark",
+            callback=self._delete_bookmark_context_menu_callback,
+        )
         self.bot.tree.add_command(self.book_mark_context_menu, guild=discord.Object(bot.guild_id))
 
     @staticmethod
@@ -105,6 +108,26 @@ def build_error_embed(message: str) -> discord.Embed:
             colour=Colours.soft_red,
         )
 
+    async def _delete_bookmark_context_menu_callback(
+            self,
+            interaction: discord.Interaction,
+            message: discord.Message
+    ) -> None:
+        """
+        Delete the Sir-Lancebot message that the command invocation is replying to.
+
+        This command allows deleting any message sent by Sir-Lancebot in the user's DM channel with the bot.
+        The command invocation must be a reply to the message that is to be deleted.
+        """
+        if interaction.channel.type != discord.ChannelType.private:
+            raise commands.UserInputError("You can only run this command your own DMs!")
+        elif message.channel != interaction.channel:
+            raise commands.UserInputError("You can only delete messages in your own DMs!")
+        elif message.author != self.bot.user:
+            raise commands.UserInputError("You can only delete messages sent by Sir Lancebot!")
+
+        await message.delete()
+
     async def _bookmark_context_menu_callback(self, interaction: discord.Interaction, message: discord.Message) -> None:
         """The callback that will be invoked upon using the bookmark's context menu command."""
         permissions = interaction.channel.permissions_for(interaction.user)