How do I get a form 4852 off my tax return Ifound my 1099-r form

You will have to delete the Form 4852.

See: How do I delete forms in TurboTax Online?

After deleting the Form 4852 log out of the program. When you log back in, you use the Delete a Form tool to see if it has been removed from the list of forms in your return.  If it has, go ahead and enter the Form 1099-R.