Removing glue from Iron-on Patch, not on clothing. Sewing Machines Parts and Sales in Los Angeles

Not sure of this belongs here, but wasnt sure where else to turn…
Anyways, i sew patches onto my denim jacket, and will be doing so with a leather one soon. I’ve sewed a couple iron-on patches by hand and it was very difficult pushing the needle through the patch. Only after did i think to iron it on then sew…but my question is, is there anway to remove the glue from the patch itself so i can sew it on easier?
Mainly because the idea of ironing on a patch to the leather sounds terrible. Thanks for any and all answers!