I just changed three Racors with the see through plastic bowls a few days ago.
If the plastic bowl is really tight you may ruin the new Racor trying to take it off.
If the Racor is old, use a filter removal wrench on the Racor, and the biggest pliers (the kind that open real wide "goose neck"/groove joint plier - like at this link = Channellock Tools : Pliers, Wrenches and Screwdrivers
(also called water pump pliers)
in your tool box
to grab the plastic bowl. Than turn both the Racor and bowl together "counterclockwise").
They should come off together - easily. Sometimes the plastic bowl will move slightly. It happend to one of mine that way when I was removing them a few days ago.
I use a vice to remove a Racor from the plastic bowl that won't separate from each other. Usually you ruin the Racor filter and save the bowl.
With a friend (I.e., another set of hands) you could do it with the filter wrench and the groove joint plier with a towel - "wrenching/twisting" in opposite directions gently.
be carefull not to crack the bowl.