This message ahs nothing to do with a real problem of httpd. If you want to know why httpd does not start, take a look into the error log of the webserver.
Is there a way to uninstall ISPconfig 3. Could not find information on the forum only for ISPConfig 2
Use the uninstall script which is in the same folder then the install script. But uninstalling ispconfig will not fix your httpd problem.