First of all we need a XRPL account with a Authorized Minter.
To know if your XRPL account has a Authorized Minter assigned you can check it on Bithomp. Visit your address and check your Account Information box!

After confirming our XRPL account has a NFT minter assigned. We can unsassign it just following this small tutorial. Don’t do this if you are minting a collection with the assigned minter at that moment!
For this tutorial you need Internet and a XUMM wallet with your XRPL account in there.
Visit XRPL.services. Enter in the XRPL Tools section.

Look and click on Raw JSON Transacctions block.

It will open a box with a “Select a template” box:

Select AccountSet in the Select a template. It will load a template for this type of transactions.

Now, we introduce this text (you remove “youraccount” for your r-address, for example rWYkbWkCeg8dP6rXALnjgZSjjLyih5NXm):
{
"TransactionType": "AccountSet",
"Account": "youraccount",
"ClearFlag": "10"
}
If we want to remove the Minter from rWYkbWkCeg8dP6rXALnjgZSjjLyih5NXm this will be shown like this:
{
"TransactionType": "AccountSet",
"Account": "rWYkbWkCeg8dP6rXALnjgZSjjLyih5NXm",
"ClearFlag": "10"
}

Final step is sign this transaction with our XUMM wallet. Clicking on the blue “Send TRansaction to XUMM”. Scan the QR and accept the AccountSet transaction.

Thanks to XRPLServices, Bithomp and XUMM to make this possible and making easy to interact with XRPL. If you want to support them you can buy a NFT of my collections and I will send 100% of the sale to them or send a donation to their projects in their webpages donations sections.
More info: https://xrpl.org/accountset.html#accountset