try mo to
from https://thenextweb
com/basics/2020/07/01/how-to-delete-your-old-facebook-posts-in-bulk/
The procedure for deleting old posts is similar for all three apps.
So that’s a bonus. Here’s how you can do it:
Open the Facebook app on your phone.
Got to your profile, and tap on the three-dot menu.
Go to Activity Log > Manage Activity and tap on the popup that says Your Posts.
select all then tap delete or trash icon
Deleting or archiving old Facebook posts
All archived or deleted posts will show up as labels in Your Posts sections. You can tap those labels to see your archived or deleted posts.
Facebook will retain your posts in the recycle bin for 30 days in case you deleted a post by mistake, and want to restore it. It’s a bummer that there’s no option to bulk delete posts on Facebook’s desktop site. Hopefully, the company will roll out this feature soon. Till then, you can hide all of your sins under the carpet through mobile apps.