Over time and doing tasks you need to archive the list.
Archiving a list does not mean deleting tasks, but you can rearrange your work space and you can recycle it whenever you need it.
To archive the list, click the gear icon in the top bar of the list and select "Archive".
It is possible to archive lists and tasks for people who have access control to the page
Click on the top of the page to see the archived lists so that it's blue.
then To recycle the list, click the gear icon in the top bar of the list and select "recycle".