u/Alarmed_War6135

I have an approx 8 year old HP zbook laptop which is decent spec running i7 and Windows 7 Professional. I want to completely wipe it so it can be sold but it seems there isn’t a simple way of doing this as with newer versions of Windows. Could I just delete all documents and uninstall all programs? I mainly just want to remove any personal information and potentially speed it up if anyone buying it wants to use it rather then use for parts.