Dealing with CRT discharging and subsequent disconnection is so easy most of us miss it. I think it was Dr. Tom Lee who once gave this sage advice:

Power-on your SE/30 and crank up the brightness all the way. Yank the cord. Wait a second or two. Now the CRT is discharged and you can pry off the suction cup with a screw driver.

I've tried it, and it works well.