CComment docs
Overriding any ccomment template
Overriding any template in CComment5 is extremly easy. We follow closely the joomla template overrides conventions and if you already know how template overrides work, then it should be really easy for you to make changes in CComment5. If you don't know how template overrides in Joomla work we advise you to have a look at the following links:How to override the output from the joomla core&Tutorial: Free yourself with Joomla template overrides.
The templates in ccomment are located in components/com_comment/templates. Let us say that you need to override the html of the default template. The template itself will be located in components/com_comment/templates/default. You can copy the whole folder or just files from the folder to templates/your_joomla_template/html/com_comment/templates/default. Default in this case is the name of the template. If our template was called XYZ we would need to copy it to templates/your_template/html/com_comment/templates/XYZ
Once you've copied the template you can start and make modifications to it.
You don't have to copy all the files in the template folder. You can just copy the file that you need to modify.