I want to reset my bootcamp Windows 7 to factory setting. How would I do this without damaging or effecting my Mac data?

If you want to erase the BootCamp Partition, you'd use the Bootcamp utility.

Then that part of the Mac's hard disk drive may be available for use in OS X.

{Or, if you want to install a clean Windows 7 in the same BootCamp partition

you'd use the BootCamp utility to erase/install Windows in the same location.

There is a BootCamp Support section in Apple Support online, and also there

is a fairly OK ASC discussions area specific to that purpose. }

But you may have to check to see if the partition map is correct for Mac OS X

after you've used Bootcamp utility to remove Windows and the partition map.

If you do not use the BootCamp utility to remove Windows, correctly or if a

different method to install Windows was used, you'd have to move your Mac

OS X system and applications off the computer to an external hard drive by

use of a clone utility (carbon copy cloner, or superduper, etc) then use the

OS X disk utility (from running clone, is easiest) to erase the computer's HD

and then correctly partition map and format the hard drive for Mac OS X.

At that point, the entire drive would be erased to reclaim any untouched

partitions from alternative Windows utilities that were used, or not used in

the time frame of proper opportunity.

I've had a few Macs that had been partitioned for Windows and found one

second hand MacBook to have more actual hard disk drive capacity than

the previous owner and the Mac HD info suggested on first glance. About

70% of the drive had been a Windows partition, but was invisible to OS X.

So that turned out to be a lucky find, it was like installing a larger HDD.

The wording of your question leaves a lot

of important information out of the picture.

Good luck!😐

edited

Following thread could help your question.

https://discussions.apple.com/thread/5191321?answerId=22559515022#22559515022