Put the flux over flat display cable contact soldering line. I marked it with green arrow at second photo. Turn the soldering iron to 300C (570F) degrees. Heat the soldering line from one side and with tweezers carefully pull the loosened cable away from circuit board.

Be extremely careful on cable removing at top side in photo. There are two dead end tracks with pads that can easy lift up or get torn off and go away with display cable. Try to avoid that.

Work will be easier when circuit board is held in some soldering helping hand tool with soft coating around grips or in little vice. Be careful though and don't destroy any components on circuit board.

Flat cable desoldering is easier with shovel type T12-1402 tip or other similar flat wide tip. This will melt the solder in all cable width at once. Thus make removal process shorter and stress the circuit board less.

If you have difficulties with melting the solder: 1) use more flux. 2) turn soldering iron temperature 10-20 degrees warmer - many soldering irons show larger temperature number than tip actually have. 3) Use even more flux - do not skimp on it.

After cable removing clear solder remains from pads with desoldering braid. Clear the board around pads with cotton bud, soaked in PCB cleaner or isopropyl alcohol.