This support article will help you identify and manage files in your Google Drive that you may no longer need. This can free up valuable storage space, making it easier to find the items you use regularly. By cleaning up your Drive, you'll be able to store the files that are most important to you 

Identifying the largest files in your Drive.

Go to the Storage section of Drive. The list will default to the largest files first.

Identifying files of a specific type.

You can use the advanced search in Drive to identify files that can use up lots of space like videos and audio files.

1. Log into Drive dashboard and click the advanced search icon  to the right of the search field at the top of the page.
2. From the Type drop-down menu, select Video or Audio.
3. From the Owner drop-down menu, select Owned by me. 
4. Click Search.

Finding unused files.

Use the advanced search options to find files that haven’t been modified for a long time.

1. Log into Drive dashboard and click the advanced search icon  to the right of the search field at the top of the page.
2. Select Owned by me from the Owner drop-down menu.
3. From the Date modified drop-down menu, select one of the options.
   1. You can choose Custom... and use the Before date.

Finding copies.

Copies of Google Docs default to the title "Copy of" followed by the rest of the original title. Perform a search for "Copy of" in Drive to find some of your duplicates.

Tip: Click List view in the upper right corner to make it easier to identify duplicates.

Trashing files.

Right-click on any file in Drive and select Move to trash. The file will be moved into your Trash and remain there for 30 days before it's permanently deleted.

Note: Files that are not owned by you will only be removed from your Drive. Files that are shared with you but owned by someone else do not count against your storage.

Permanently deleting files.

Files that have been moved to Trash will automatically be deleted after 30 days. They can be deleted earlier.

To empty your entire Trash, click on Empty trash when viewing your Trash folder.

To delete a specific file, right-click on any file and click on Delete forever.

Note: Data that sits in your Trash still counts towards your storage.

Note: If you have a lot of trashed files, it may take a long time to empty your trash. Consider purging files in smaller increments.

Thanks to https://uit.stanford.edu/project/google-workspace-optimization/clean-up-drive