Dell instruction can be confusing but I had done many cmos clear on Dell desktop, most of the time solving issue.  It should be super simple in steps.  Disregard the Dell instructions on that publication.  Just do this:

Unplug power cord, move jumper x 5-10 sec, move back.

while doing this, leave battery in place.

the cmos battery service is a different approach to clear cmos, and it should not be considered equivalent to the jumper method.  When you want to do a thorough cmos clear, I find jumper method is more reliable.

it is always good idea to replace cmos battery w a new one.  If bios is able to keep date updated after you unplug power cord for hours, that would mean battery is still good.

@redxps630​ 

Many thanks for clarifying this for me.

All the best.

@redxps630 

If the PC uses a jumper to reset BIOS, isn't the PC suppose to be plugged in for 10 sec. while the jumper is on the RTCRST or CMCLR pins?

I know it works though because I did it.  PC does not turn on to run the 4 or 5 sec. self-check when power is introduced.

power cord plugged in during jumper reset is not required.  many Dell models clear cmos instructions mention unplug the cord.

in general touching mobo when it has 5v SB on when power cord is plugged in is more risky than a completely powered off board.

@redxps630​ 

No, no, no - I didn't mean have it plugged in while moving jumpers.  I meant just plug it in for 10 sec. while jumper is on RTCRST pins, then unplug again, then move jumper back.