Pipework confusion

Hi All
Looking for some advice from some pool experts.
Just purchased a home with pool and have been trying to get my pool dialed in. I am doing the maintenance myself after firing an incompetent pool company, (which is another long story involving green pools and filters at 38psi.)

Recently a couple of sections of the above ground plumbing at the equipment has sprung a leak. The first leak is within the gas water heater, which will be simple enough to bypass, as I have no use for the heater.
The latest leak is on a pipe I have absolutely no idea of why it exists. This is where I need your help.
This pipe tees off from the main pump and goes directly to the returns, bypassing the filters and chlorinator.

For some reason I cannot post pictures to the forum, but hopefully these link through ok.

https://www.flickr.com/photos/125327010@N08/

Question is, can I simply remove this line and cap it off, or does it serve a purpose.

Thanks