Hello
I am Prakash and happy to help you with your question, I'm a Microsoft consumer like you.
Please fist stop syncing of your OneDrive from your PC.
Please go to OneDrive online or Web version and try to Remove several files or folders at a time then Empty recycle bin. ( You have repeat these steps until you delete all files\folders )
In case of additional questions, reach out back to us, and we will be happy to help and try our best to resolve your issue.
Give back to the Community. Help the next person who has this issue by indicating if this reply solved your problem. Click Yes or No below
Best Regards, Prakash