How to remove door hinge cap?
It looks like a fixed pin hinge with security caps on both ends. If so unscrewing it from the jamb or hinge is the only way to take the door  down.

Circled in red  are two pins or screws look at both sides see if there is a way to unscrew them.  If the set pin/screw does not extend through the entire hinge or have a place for using a tool to unscrew it is a security hinge that has a non removable pin.
Your hinge is found here on the manufacturer’s website. It is a very good ball bearing hinge that should not need any tweaking. Bending it would surely compromise the smooth operation.  The wall the door is mounted in may be a bit out of plumb causing the door to swing open. I would investigate installing a door closer on it as @RedGrittyBrick suggests.

Edit: I asked about this hinge on Amazon UK it is s fixed pin hinge not designed to be separated.