If you are working with a maintenance view object, use the Attributes and mark the field as Hidden. Re-generate maintenance dialog afterwards.
If you are working with a table object, then you can simply remove the field from the generated table control. Also remember to remove the field from the FIELD - CHAIN statement in the PAI.
But, in such a case, remember that you should manually maintain some coding on the screen, to fill up/read/change the value of your hidden field programmatically.