hmmm....
I guess it depends on if you want to suppress the entire subreport, or you want the subreport to run.
If you want the subreport to run, but it is in a section that you want to suppress, the easiest solution is to move the subreport to its own section.
If you don't wnat the subreport to run, just supress the section.
If what you want to suppress is in the subreport, then, I guess it depends on if you want the subreport to run, or maybe the field you need to check is in the subreport, so you need the subreport to run, but you want to reclaim the empty space that is used by the 'now' suppressed subreport... in which case the standard answer is to put the subreport in its own section, and in the section expert for this section check 'suppress blank sections'. Then when the subreport is suppressed, the section is blank.
obviously there are lots of variables that you haven't mentioned...
in general Section Expert is your friend.
HTH