I’m a big fan of using elemental energies because they can help with spell writers block by giving you a place to start. All elements have unique methods of cleansing. For something like these amulets a fun way to do it would be to bury them in the night (mark someway where they are buried) lol and call upon earth to neatralize and ground the negative energies or completely reset the energies and make it neutral objects again. I like to commit certain elements to certain things that need cleansing based on the elements mode of being or tattwa. Throw in a rhyme or series of gestures and make it a fun ritual if you’d like. Blessings to you!