How to disconnect Door Wiring harness?

[CrossTrek]

Final Update: Hello!! After a long long fight that i lost xd trying to disconnect that connector into the sheet metal i decided to cut the plastic boot to access to the cutted wires, so there it were, 3 wires cutted : brown audio, gray and white central lock.
I had to cut the wrapping to release all wires and add new wire before weld them.
Also i had to remove the door stopper to have more space before work there.

So i added new wires and weld them with the old ones, after that i isolated the weld area with 3m vinyl tape and back to assembly the door...

It is not the most professional finish but works!

Some photos



Thank you very much for you help!!!
Cheers!