I think the OP's problem is that they tried to glue an S-Pen and now have a blob of (set) glue blocking the hole.
The question is, where in the hole is the glue (i.e. how viable is it to use a narrow metal probe and pick it off)? You'd want to avoid the mechanisms that hold it in or detect when it is inserted, so you'd have to proceed with care.
Otherwise, if you were considering a front screen replacement, how about getting the S-Pen housing replaced? That might be a cheaper repair, after all.