I gave it in the option that says cancel transaction to prevent it from being sent and then I got a window that said "your balance will be corrected after the next synchronization with the network "The issue is that 12 hours have already passed and the balance remains uncorrected, I don't know where these btc's are
I recently tried that option in Mycelium, and a new synchronization made the unconfirmed transaction show up again. I guess Mycelium picked it up because it's still in mempool.
it is not on the blockchain either
If you check either your sending or the receiving address on
Blockchair.com, you should see what really happened to the coins.
If you want to wait for the transaction to completely disappear from mempool, it can take several days (or longer), but only if Mycelium doesn't continue broadcasting the transaction. It may confirm in the meantime, which means funds will be on the address you sent it to.