Antonio, before you start a clean install, be sure you have a bootable backup of your hard drive.
If you use Google, be sure that all your passwords and info have been sync'd to you account. The same goes for iCloud.
You'll be erasing all your Preferences so you might take a little time and write down the settings for your email , Network and Mac accounts (in Preferences and Mail client).
I make a list (or screenshot) of my Applications folder and any passwords/activation codes you'll need to get them running.
BTW, have you installed an SSD or do you have the stock HD? If it's an SSD there's an extra step in installing HS (new file system).
Anyway, here are the instructions on doing a clean install. You'll need a USB thumb drive at least 8G to "create" an installer.
https://blog.macsales.com/42502-tech-101-how-to-perform-a-clean-install-of-macos-high-sierra
If you've never used Terminal, you're going to just be copying and pasting so don't sweat it.
If the commands in Terminal seem to be taking forever (over a couple of minutes) you might need to hit "enter".
Here's the High Sierra download.
https://support.apple.com/en-us/HT208969
Don't over complicate things. These instructions are pretty complete.
If you open High Sierra and there's a bunch of stuff missing, you have it on your back up. Just open the backup in another Finder window and drag and drop your Desktop, Documents, Pictures, Music, Movies to the new folder on your MBP.
All this is kind of a pain the ass but in the end, it should be like having a new machine.
Feel free to PM me with questions.