El Capitan not installing - This disk is used for time machine backups
I downloaded El Capitan today to install on my 2010 Macbook Pro in order to download the latest version of iTunes, so that i can sy;nc my new iPhone, which won't sync with my itunes Version 11.4 (18).
When I select the disk to install, I get the message "This disk is used for Time Machine Backups" even though it isn't, I use an external hard drive. I can't then select the Install button.
I have already read this thread El Capitan Won't Install - This Disk is used for Time Machine Backup regarding the problem and searched for files like timemachinebackups.backups did not find any...
Unfortunately I am not a computer pro :/ and I have no idea how to solve this problem.
Hope someone can help me, thanks!
Rena
MacBookPro