Theoractically is possible, but the result may not be what you expect. As the sound may change totally. This is because of the varying thickness from the center to the edge which contribute to the sizzle effect. Also the hammering and processes done at manufacturing. So too much trimming of makes the cymbal become like a bell sound.
Also, unless you have lobang to do so cheaply, have to be a real metal works expert. As these although is brass or brass like material, are infact metal alloy, pretty hard stuff. I tried diy during early days, found out the hard way.