Follow this guide to make a custom cotton swab.

You can also use dental picks with barbed tips (non-flavored).

You can use a normal cotton swab, but most are too thick and have loose cotton that can snag on sharp edges.

Apply a few drops of highly-concentrated isopropyl alcohol (>90%) to the cotton.

Insert your tool between the middle contact pad and the perimeter of the USB-C port itself.

Don't force the tool into the port, as you risk breaking the middle contact pad.

Slide the tool along the perimeter of the port to clean it.

Wait a few minutes for the isopropyl alcohol to evaporate before plugging in your device and testing it.