If there are some medical bills on your credit report that should have been paid by your insurance company how can you have these removed?

You can attempt to have any item removed from your credit report by the same method; writing a letter of dispute to the bureaus.

"...should have been paid by your insurance company..." is not a valid reason for dispute. If you were to write with this reason, (most likely) the accounts will be verified and they will remain on your credit for 7 years from the date they were defaulted.