Altium: How can I edit a component from a library
As @The Photon has already pointed out, you can copy any component from any library (PCB or Schematic) into your own library to modify them as you like.




Open the libraries







Copy the specific component from the source library







Once you have the component on the clipboard Paste 1 Components option will be available







Finally, rename the copy






And after these steps you can edit the component in your own library.