Welcome vadimo
To be honest, there isn't really much of anything that you can uninstall. Ut's not like computers you buy from OEM's, the surface devices don't come with any additional software installed, e.g bloatware. As such, re-installing windows will not really accomplish anything. Easiest thing to do is simply buy a microsd card for a couple of quid.
One thing to keep in mind is that when windows performs a build update, you'll end up with a system.old folder which can be as big as 20gb. If you're happy with the update and do not wish to roll back, then run disk cleanup to remove this.