Home Improvement
I live in a rental property that has a tiny yard out back. I’d love to paint it just to brighten it up a little more for sitting out in the 3 days of UK sun, but don’t want the landlord to take a hissy fit and steal my deposit. So if I did paint it, is there a (easy) way to strip it before I leave? 
Have you considered contacting the landlord to see if you could just paint it with their permission because if I was a landlord and my tenant wanted to do something like that, assuming they did it properly, I wouldn’t be upset. It would probably be considered an improvement.
No. Once it's painted, it's painted (otherwise any sort of harsh weather would strip the new paint).
The only thing you can really do is to repaint in that lovely gray before you leave.
Thought that was going to be the answer ☹️
It’s just the gross sloppy cement colour at the minute. Maybe I’ll give them a call and see if they’d be ok with it haha
The other thing you could do is a temporary something that you can remove when you leave, like a trellis with plants or a weatherproof print of something.
You can buy Ficus trees in pots (easy care, no mess, propagate easily) pretty much anywhere in the world on local market places (facebook, gumtree, craig's list, etc) and use them to block/soften the wall and bring in some colour i.e. green leaves + pot colour. A few of those with some string/fairy lights and poof ... endless tranquility! (individual experience may vary).
Example:
You could get some pretty thin sheet rock or maybe play wood, lay them on the ground on some cheap painters plastic sheeting then paint a mural or whatever you want, then when dry you could mount it directly to the wall. Just unscrew it when you leave and voila.