IF you have a good reason to not let sysupgrade do a full install (space? on my RPI that's the case), you can simply
sysupgrade -sfn rm /home/_sysupgrade/x* reboot
IF you have a good reason to not let sysupgrade do a full install (space? on my RPI that's the case), you can simply
sysupgrade -sfn rm /home/_sysupgrade/x* reboot