Feature:Clearing Completed Tasks efficiently

[GAITURI]

Description
In the current app, when a user marks a task as completed, it remains in the list. The app should have an automatic way to remove or clear completed tasks, the removal could be immediate or after completion or using a "Clear Tasks" button.

Steps to reproduce

1. Create a few tasks
2. Click on a task to mark it as completed
3. Observe that it stays on the list.

Expected Behavior
Once a user completes a task it should either disappear automatically, or a "Clear Tasks" button should be present to remove the completed tasks in one click

Suggested solution
Generate a function that automatically detects completed tasks and removes them off the list