You may use the following information to purge the mod_pagespeed cache.
There are two methods for purging the mod_pagespeed cache.
cPanel's provided version of mod_pagespeed has the new method enabled by default, although it requires additional configuration to actually make use of it. Please review the official documentation for instructions:
You may also enable the legacy method for purging the cache with the instructions found in the official documentation:
If you are not sure where to edit the mod_pagespeed documentation to configure these settings please see the following guide: