I'm definitely lacking in electrical skills, so please help me out on the right procedure here. I have two switches controlling one light. I'd like to REMOVE SWITCH A and completely control with SWITCH B. I've attached the switch wiring as pictures below, the red wire on switch B is one wire shared with another, unchanged switch in that box:
Turn off all power before starting any work. OK switch B can remain in place but you have to determine which of the two orange travelers is hot when switch B is in the top (ON) position, then disconnect and tape the other orange wire. Remove switch A and wire nut the yellow wire to the hot orange that you did not disconnect from the other switch. Tape the other orange. You'll need to get the correct cover plate for switch A to cover up the unused gang.
It's always a good idea to put a note in each of the two boxes you worked in describing what you did for future reference. It might just help you, or a new owner, in the future.
If all you want to do is disconnect the switch A and put a blank in it's place then remove the wires from the switch and connect the yellow wire to either orange, and cap off the extra orange. If that makes switch B upside down then swap the oranges at switch A location.
If you intend on eliminating the junction box for switch B or eliminating the conduit between the two then better pictures are needed of wires entering conduit are needed to see if that is possible.