An easy way to remove admins from Facebook Business Manager without waiting 7 days.
When trying to remove an administrator in the usual way, a message is displayed:
“You’re a new admin in this business. For security reasons, you must wait 7 days before removing an admin. Please try again later.”

Removing a BM administrator without waiting
Go to your Business Manager and copy its ID:

Follow the link https://business.facebook.com/confirm_business/?business_id=, adding the previously copied Business Manager ID at the end:

Opposite the administrator you want to remove, click “Remove”:

In the window, confirm the removal by clicking “Remove”:

The unnecessary administrator is removed:

Also, check out the materials: