What kind of monitor?
You might be able to do it, but if you have to disassemble the monitor, go ahead and discharge.
It's funny...I've been working with arcade monitors for a little while now, and if it hasn't been on for a while (say more than an hour) I don't bother to discharge. I just grasp the cap firmly, pinch and twist.
Putting it back on, I flex the cup backwards, exposing the anode. I touch it to the hole in the tube (keeping my fingers well out of the way) and then take it away. Pinch it, and put it back on.
Now, if it *has* been on in the last hour, I ALWAYS discharge. Man, some of the *snaps* that come from it are suprising!