How do I claim my bitcoin cash (BCH) from a single address Mycelium wallet?
First you have to export your Mycelium master seed:
Then you need to import the master seed into the bitcoin cash version of electrum wallet, which is the electron wallet. This can be done by choosing "BIP39 Seed" in the options, during the import.
see this post for details.
Note: For security reasons you should empty your bitcoin wallet before claiming your bitcoin cash.
You simply import the private key of the single adress wallet into a bitcoin cash wallet such as https://electroncash.org/