How can I combine two wall switches into one?
Assuming that the black and red wires that are connected to the same side of the switch power either light fixtures or standard outlets...


Mark the wire that's on the side by itself with tape or something else.
Remove all wires from the switch.
Clip the loops off the two unmarked wires, then strip them 1/2" to expose fresh wire. 
Use a suitably sized wire nut to combine those two wires, along with a 6" length of #14 or #12 solid copper building wire. 
Bend a loop into the pigtail wire using a needle-nose plier or similar.
Install the two loops onto either screw of a standard two-way switch, wrapping the loop clockwise under the screw head. The loop should fit snugly against the screw shaft and wrap at least half way around.
Install the switch and a cover plate into the box, tucking the wires in carefully so as not to kink them.