How do I change these LEDs?

I have (had) the same type. The LED chips had a disappointingly short life... Initially replaced 2 fixtures with an equivalent, but kinda pricey for what they were... Created an alternative...Cabin Bright sells a NICE replacement LED chipset for ITC fixtures - see https://www.cabinbright.com/product/itc-fixture-replacement-led-set/ - I replaced the PCB in the original fixtures with a piece of roofing aluminum I cut to the same size. Drilled a 1/4" hole for the wires thru the center of the replacement square of aluminum, then adhered the new chipset right to that (serves as a heatsink, too). Re-installed the original fixture with the new board - great results! Available in various temperatures, too.