It would be better to get a connector pin removal tool or make one from a thin screwdriver or hairpin. Keep track of the wires since a mix up can cause an electrical disaster; tag both the wires and the connectors.
Stagger any solder splices to avoid forming a thick lump in one spot on the cable.
He means IF you decide to cut and re-solder them back together, not to cut all the wires in a straight line, leading to a large lump where they were all re-soldered in the same area.
But using a connecter pin removal tool is the preferred way of sleeving a psu.
anywhere I can get a removal tool for less than $10 after shipping, because there are literally no good tutorials on DIY cable removals