Can I burn BTC for XCP?

No, but at the moment you can still burn tBTC for tXCP on the Bitcoin Testnet for testing Counterparty features.

If you wish to change to using the Testnet, refer to Can I use the Counterparty/Bitcoin Testnet in Freewallet?

To burn tBTC for tXCP, make sure you are switched over to using the Testnet and then right click your BTC balance.

A pop-up will then appear to choose how much tBTC you are choosing to burn.

In the past, at the very start of Counterparty, a specific amount of BTC was burned to create the entire XCP supply. Read more about this Counterparty initial Bitcoin burn process here.