Depending on your configuration you don’t need to solder all the headers. So skip that parts you don’t want.
Start with breaking the 14p header into 3 sections.
- 2x 5 pin
- 1x 2 pin (Already separate)
- 1x 4pin
Take the 4pin header and remove the middle two pins with pliers or you can just push it on and it will push the middle two out. Then holding one side with your finger you can solder from back.