Need help disassembling Groehe shower thermostat
Unscrew the cap and pull off the brass collar that will reveal the plastic grey temp handle.  Then there is a green clip that is split.  Pull the green clip out and the remaining handle components will come off.  I think it’s component number 1.4 in the parts breakdown.
Visit the grohe website for that trim and it’s really obvious and easy to get it apart.
Good luck!