Go to the post insights and there should be a button to Delete Ad there
Open ad insight then scroll down u will get delete option then u can delete that ad after that u can delete post.
Understood but as I mentioned before. Check the error message
Yea that what I am saying go to ad section click on the view insight then scroll delete ad first then u can easily the delete post. Error is showing cuz u not deleted ad.
U can also try from other device if it’s showing something went error
Doesn’t work from other device
The solution I figured out is to go to Your Activity > Photos & Videos > choose the post then delete 
Should convert account from business to personal as @DigiX said to me
1 Like