The best way is to use P2P exchanges if you are converting the BTC to cash. You might not be affected so much by the withdrawal fees, as most of the traders in those platforms try to offer the best rates.
10 Bitcoin is not an amount that you can cash out using P2P without raising suspicions.
It is about $700,000, and of course if you start receiving this money from multiple accounts that you have no connection to, your account will most likely be closed or frozen and you will be asked about the source of the money, especially if the total annual deposits to your account are less than $100,000.
The best solution is to search for KYC exchange services and pay your taxes legally, as it is difficult to hide this amount or to trade via cash with small amounts around $10,000 per transaction (70 times).