Yes, you are certainly permitted to rebrand Centova Cast, however this is outside of the scope of our support services -- we do not provide support/assistance with editing the templates/CSS, nor with any problems that may arise as a result of modifications that have been made.

Modifying the Centova Cast interface may interfere with the operation of Centova Cast, and cause issues to arise which may appear to be unrelated to your modifications.  Should our support representatives feel that your modifications are interfering with the proper operation of Centova Cast, we reserve the right to discontinue technical support for any issues you experience with Centova Cast after modifications are made.

Having said that, we have made available some basic customization tips in the following knowledge base article:
How do I rebrand/customize the Centova Cast web interface?

If you only want to replace the Centova Cast logo with your own, please see this article instead:
How do I apply my own logo to Centova Cast?