Street Cup Handlebar Replacement

hi all,
I need technical support to replace my streetcup handlebar with a clip on handlebar.
I dismounted and replaced correctly everything (as you can see in the picture 1) but I would install the original bar end mirrors and to be able to do that, I need to dismount the bar end clamp from the original handlebar (picture 2).

Is there somebody that can help me to dismount that part from the original handlebar?
Many thanks in advance

 

Thank for your suggestion