The character is not a question mark. The ls utility will replace non printable characters with ?.
Would you want to delete both those files, you could do
rm ./*ssolve*
This would first expand the given pattern to all the filenames matching it, and then rm would remove them. Be more specific and specify a longer part of the filename if there are files that you don't want to delete that matches the above short pattern, e.g. with
rm ./*ssolveIncpUL46pK*
This is assuming that you are located in the same directory as the files that you want to delete.