which program are you talking about, GPSResults or GPSspeedreader?
They will both crop sessions, but do it differently
So with speedreader, you highlight the section on the speed graph, then tracks>delete selection, or either of the other two options depending on what's appropriate.
I don't have a licensed copy of GPSResults on this OS, so if that's what your using, I have to boot into an older version, to see the process. This old memory is too unreliable.
I've had a look at the unregistered version of GPSResults, and it looks like, using the shift key you can select a section on the speed graph, then >edit>cut
In GPS Results you can click Extras | Set Timelimits, enter hhmm for each end, then File | Save Trackpoints. Choose a new filename and upload that.
As a newbie to this stuff I am finding that all the names of the software and platforms are too similar for my addled brain. It's a shame for me that there isn't a bit more differentiation between the various names. I guess it's driven by the way that folks search for stuff so the names have to look GPSey and Searchy and Speedy? Anyway, I'm getting there....slowly.
I am currently using GPS Speedreader as that works on my Apple iMac quite well. It does allow editing/cropping and it seems straight forward but I cannot see any way to save the edited file. After editing it uploads to GPS Team Challenge really quickly and easily but the remaining file is not updated, so if I then try to upload the cropped file to GPS-Speedsailing, it's the old uncropped file that uploads. Hence I am currently the fastest sailor in the world due to driving down the freeway with my GW 60 still recording!
don't worry Steve you're not the first and won't be the last.
Peter is working on a save function for GPSSpeedReader, (he thought for a while about a more distinctive name, but nothing appeared)
In the meantime send the file to me and I'll send it back to you cropped
Thanks for that offer Decrepit. Sorry but I can't seem send a file via seabreeze, how do I get your email? P.S. I wouldn't ordinarily be this focussed on one session but it was my first real sail for 25 years and I "sort of" went OK for a first go in **** conditions. In fact when I looked at the results for the "Oldfarts section" on GPS-Speedsurfing, I noticed that I was actually faster than Bjorn Dunkerbeck's Dad, Eugen, who is also 72 like me, so I want to post it on that site for a laugh and for posterity.
Hi Steve, I PMed you a few days ago with my email address, check your "messages" on this site.
Seems like you need a trip to Lilacs, have a look what Waricle has been doing there, this January.

Waricle is also your age. Conditions are so nice even us old farts can go well.
His March 2020 results were from Lake George in South Australia. Another fantastic spot, well worth the trip if boarder closures aren't a problem .
WOOOPS!!!!! checked my sent box, nothing there, must have forgotten to hit "send".
No wonder I don't get answers!