Thank you for writing to the Dell Community Forum.
Upgrading to Windows 10 will not void the warranty of the system. However, I would recommend you to check if your system is compatible and tested from Dell for Windows 10.
Please let me know the model of your computer and I will check and reply if your system is compatible to upgrade to Windows 10.
You can also check if compatible Windows 10 drivers for your system are available on our Dell Support site. Also check the following link for requirements and more info on Windows 10: