If you mean you want to reinstall Windows, yes, that's doable.
It's not impossible. New PCs and laptops these days comes with a
recovery button. You can press that button and the reinstallation
process will start. It will wipe everything and start all over.
However, please backup your files before doing so.
If you mean to clean up some of the unwanted stuffs on your PC,
you can do so as well. I'm not sure which version of Windows you
are running, so I'm going to assume that it's Windows 7. I'm also
going to assume that your PC is not infected with any virus.
Because doing any of these stuffs before cleaning up your PC can
make things worse.
If you want to be sure, we will go through the procedure of
checking your PC first, followed by a performance tuneup.
Step 1
Click on Start > Control
Panel > Programs and Features
Remove any unwanted programs from there.
Step 2
Download CCleaner
and remove temp files. Save this file to a thumbdrive and extract
it.
Step 3
Run Windows Disk Defragmenter (Start >
All Programs > Accessories
> System Tools > Disk
Defragmenter)