How to remove error message “Strict standards : Non-static methods called statically”

This happens because of stricter checks in newer versions of PHP.

In any case this message is just a warning, and not a fatal error.

One option is to modify the source code of your website to handle the reported method.

Other option is to just disable the printing of warning messages.

For doing this, you have to create php.ini file in web root of your website (usually public_html in Cpanel) with following contents.

If it is already existing, add these lines at the bottom.

error_reporting   =   E_ALL & ~E_NOTICE      ; Show all errors except for notices
display_errors   =   Off   ; Print out errors (as a part of the output)

Your issue will be resolved.