How to remove diverter knob

[johnsweaver]

Our water softener grenaded internally pushing resin throughout the house and I'm working thru fixing all the problems that's caused. Next on the list is this shower that's got low/no flow. Need to open up and flush lines & replace diverter & cartridge if necessary.

Single handle valve with diverter for hand held sprayer.

How do I get this knob off the diverter? Doesn't seem to have any set screws.