I would recommend that you use DBAN to clean your SSD/HDD before selling. Because using a basic removal tool such as windows boot USB drive won’t completely delete the files.
If a hacker buys your old laptop, he could use softwares to recover the lost data.
Like they already said reinstalling windows with a USB drive will help. But you will lose all your drivers so I recommend you use a software that scan the PC and automatically finds them such as touslesdrivers (french). I personally use it