Apache failing to start after install - apache

Question

I have just starting using Linode with Centos 7. I have never created my own server to host a website so apologies in advance.
I have read every stackoverflow (and other sites) Q&A's for this problem and I can't seem to fix it.
I installed Apache2 and followed the tutorial on Linodes website. The server doesn't start and I get these following errors:
When I run - systemctl status httpd.service
httpd.service - The Apache HTTP Server
Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled)
Active: failed (Result: exit-code) since Sun 2015-11-08 16:18:47 GMT; 10s ago
Process: 15662 ExecStop=/bin/kill -WINCH ${MAINPID} (code=exited, status=1/FAILURE)
Process: 15661 ExecStart=/usr/sbin/httpd $OPTIONS -DFOREGROUND (code=exited, status=0/SUCCESS)
Main PID: 15661 (code=exited, status=0/SUCCESS)
Nov 08 16:18:47 london systemd[1]: Starting The Apache HTTP Server...
Nov 08 16:18:47 london httpd[15661]: httpd (pid 15652) already running
Nov 08 16:18:47 london kill[15662]: kill: cannot find process ""
Nov 08 16:18:47 london systemd[1]: httpd.service: control process exited, code=exited status=1
Nov 08 16:18:47 london systemd[1]: Failed to start The Apache HTTP Server.
Nov 08 16:18:47 london systemd[1]: Unit httpd.service entered failed state.
When I run - journalctl -xn
Logs begin at Thu 2015-10-22 20:33:26 BST, end at Sun 2015-11-08 16:18:47 GMT.
Nov 08 16:10:01 london systemd[1]: Starting Session 2857 of user root.
Subject: Unit session-2857.scope has begun with start-up
Defined-By: systemd
Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Unit session-2857.scope has begun starting up.
Nov 08 16:10:01 london systemd[1]: Started Session 2857 of user root.
Subject: Unit session-2857.scope has finished start-up
Defined-By: systemd
Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Unit session-2857.scope has finished starting up.
The start-up result is done.
Nov 08 16:10:01 london CROND[15635]: (root) CMD (/usr/lib64/sa/sa1 1 1)
Nov 08 16:15:02 london sshd[15647]: Received disconnect from 43.229.53.26: 11: [preauth]
Nov 08 16:18:47 london systemd[1]: Starting The Apache HTTP Server...
Subject: Unit httpd.service has begun with start-up
Defined-By: systemd
Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Unit httpd.service has begun starting up.
Nov 08 16:18:47 london httpd[15661]: httpd (pid 15652) already running
Nov 08 16:18:47 london kill[15662]: kill: cannot find process ""
Nov 08 16:18:47 london systemd[1]: httpd.service: control process exited, code=exited status=1
Nov 08 16:18:47 london systemd[1]: Failed to start The Apache HTTP Server.
Subject: Unit httpd.service has failed
Defined-By: systemd
Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Unit httpd.service has failed.
I have absolutely no idea and can't see where I am going wrong. Can someone help at all??
Many thanks!