What the folks have said above is wise, and they have given good advice.
In virtually all cases, a user commonly will prep the paint, polish to his/her best ability to perfect the finish, as the coating will lock in whatever is present on the paint for a long time.
As Corey from Carpro has once mentioned, and he should definitely know, is that Carpro Eraser was only designed to remove any possible oils from polishes used prior to coating.
That Carpro Eraser was not designed to remove any durable sealants, waxes, etc.
Thus, with that said, it will be wise to insure such is fully removed beforehand. This will insure proper bonding, less chance of any problems applying the coating, and one will get the longest durability from the coating.
It is assumed a polish, or another type of paint prep/cleaner lotion should then be used beforehand to remove any durable products previously used.