Reinstall

I'm having several problems and I thnk will be better to start from new
I want to delete the installation and begin again but when I try this the installation halts with this error Syntax error on line 1072 of /root/ispconfig/httpd/conf/httpd.conf:
ServerName takes one argument, The hostname of the server
/root/ispconfig/httpd/bin/apachectl startssl: httpd could not be started
No results found!ISPConfig system is now up and running!
Congratulations! Your ISPConfig system is now installed. If you had to install quota, please take the steps described in the installation manual. Otherwise your system is now available without reboot.
If I try to access the panel with https://xxx.xxx.xxx.xxx:81 I have error
What should I do.
Please help