I have to chime in here. I have to disagree with the solder wick for this person. It takes a gentle touch and can require more than one application of heat which we don't want for the electronics.
A good solder sucker desoldering tool will remove all that lump in one heat cycle.
Make sure the board is supported so you have two hands to work the iron and desoldering tool.

You can tape it to an old wood board or stick and put the end of the board in a small vise to hold it steady.

Have the desoldering tool ready so as soon as the solder starts to melt you'll be ready to suck that blob from the board. Use no more than a 25-30 watt iron.

After the bulk of solder is removed, check the board carefully making sure there are no solder bridges
between traces or other components.

Now cut that wire back as all have said and before tinning it, give the strands a twist. It keeps them together while you're tinning. Then solder to board.