Ok if your trying to uninstall windows like freshly install the operating system you need to:
Switch on your laptop
Straight away start pressing F12 as soon as you have pressed the power button
Go to HDD Recovery
Then chose what you want either:
A. Fresh install (this wipes your whole hard drive and partitions)
B. Only reinstall to one partition (this would be your C drive or system drive) this option does not fully wipe the hard drive or remove other partitions ( D drive or Data would be an example where you would have documents, media and other items stored to)
If you need further help depending on what version of windows your on try google.