If you want to see apache error.log file in your public_html or subdomain dir :
1) Login to Cwp with root account. 
2) Go to Apache Settings/ Apache Vhosts Template 
3) In Apache Domain Virtual Host tpl:
Add this line after  (DocumentRoot "%homedir%/%username%/public_html"):
ErrorLog "%homedir%/%username%/public_html/error.log"4) In Apache SubDomain Virtual Host tpl: 
Add this line  after (DocumentRoot "%path%") : 
ErrorLog "%path%/error.log"
5) Click Save Changes and Go to :  Rebuild  Virtual Hosts and Click "Rebuild All Virtual Hosts"

6) Alright!!  You can see error.log file in public_html or your subdomain_dir : 

