Which wallet are you using? I have not seen 0 sat/vbyte before when making transaction, it starts from 1 sat/vbyte.
I used Electrum wallet to perform my transaction and I can adjust my fee after confirming from mempool.space, and current the highest fee rate is 1 sat/vbyte. I guess you are using trustwallet that is why you don't know about whether fee is adjustable or not.
You can download Electrum wallet from their official site, create address and start using their wallets to make transactions you can perform transactions with the least of 0-1 sat/vbyte.
Is it possible to adjust the fee rate to 0 sat/vbyte on Electrum wallet? Even if it is, I wouldn't advise you to do it because miners prioritize transactions with higher fee rates. Sending a transaction with 0 sat/vbyte means it will be overlooked by the miners. It will be the last in the queue among the unconfirmed transactions, and it might even be stuck indefinitely in the mempool.