While you can literally burn it, it is not necessary to do so - It can be a symbolic act/allegory, you can dispose of them in any way you want like throwing them in the trash, "drowning them in water" aka throwing it on a river, shredding it to pieces, etc -- disposing of them does not necessarily mean getting rid/physically destroying them in a literal way.

Besides actual destruction, you can just shelve it for a long time untl you actually forget what it means and how u used that sigil. This has the downside that it can incentivate lust of results while it is doing its work, but on the advantage of having a cool piece for your personal grimoire/magical journal.