User @nc50lc already mentioned how to achieve that on Electrum application. I suggest you to re-read what he said calmly.
Yes, nc50lc explained one way to do it, but there is actually a simpler way that the OP can use to disable the "change addresses" feature in Electrum. He probably couldn't find this option due to changes in the GUI of the newer versions of the software.
That's not the point of the instructions.
It's to explain that even if what he want to do is doable, there wont be any difference when it comes with the number of UTXO that his wallet will receive even if the change is sent to the same address or a change address.
And for some reason, OP is fixated on the thought of disabling change address will fix his high transaction fee issue.
At this point, I wont add anything that's already been explained here.