Macbook pro 15" approx 2010

If the laptop is using a hard drive, then enable Filevault and let the encryption process complete. If the laptop is using an SSD, then this is not really necessary. Apple's instructions assume a Mac is using an SSD or if using a hard drive that the hard drive is encrypted with Filevault. Otherwise a user will need to write zeroes to the entire hard drive which is very difficult to do these days since Apple has removed this option from Disk Utility. Apple's instructions will leave your personal data exposed on the hard drive accessible with any data recovery app because Apple's instructions assume the data is encrypted or an SSD is being used.

Then follow the steps in this Apple article if are you selling or recycling the laptop:

What to do before you sell, give away, or trade in your Mac - Apple Support

When performing the clean install of macOS on the final step, I would suggest modifying Apple's instructions to erase the drive by using this method.....Select the physical drive on the left pane of Disk Utility and erase it as GUID partition and MacOS Extended (Journaled). You may need to click "View" within Disk Utility and select "Show All Devices" so that the physical drive appears on the left pane of Disk Utility. The physical drive will be identified by its make & model such as "Hitachi HTxxx" or "Apple SSD....". After erasing the whole physical drive continue as described in the Apple articles to select "Reinstall macOS".