just got a disabled iPhone 6 how do I undisable if I never synced it to my computer

You will need a SIM to activate that phone.

Restore your iPhone, iPad, or iPod to factory settings - Apple Support

As Michael said above if you run into an Activation Lock screen you will not be able to activate it.

You can erase it by restoring it in iTunes. However, with it still linked to their iCloud account you’ll never activate it and use it without their AppleID and password.

Your friend needs to follow the steps in this Apple Support Link: What to do before you sell or give away your iPhone, iPad, or iPod touch - Apple Support

It's still likely activation locked and you simply cannot bypass activation lock. It's very unlikely you'll be able to use this for anything.

So did you buy it two years ago? If not, you got ripped off.

Why would you pay $800 for an iPhone that you are only going to use for games and texts?

Get a SIM (it doesn't have to be a working one) and if your friend did clear that phone properly you should be able to restore it as shown in that link. If instead it displays an Activation Lock screen you will need the original receipt for the iPhone from an Apple Store or authorized Apple reseller, a copy of the sales agreement selling it to you, a death certificate, and something from the Executor of the estate saying you are now the legal owner.

So how long have you been paying for it and how much of the $800 had you paid? Why didn't you have the phone before now?

Jackhubbart wrote:

And I will be mad as **** I played the person I got it from 800 dollars

In your initial post you said you got this from a friend. If your friend doesn’t know the AppleID to remove activation lock, presumably they’d at least refund your money?

It does beg the question why anyone would pay $800 for an iPhone 6. The going used rate from online sellers is about $200-$250 (e.g. gazelle.com).

I hope that wasn't US dollars

Get your money back. Why would you pay that much money for a phone that is now over 4 generations old in iPhone generations?

So you paid $800 for a phone that is 4 generations old and used when you could buy a brand new iPhone 8 64GB for $699? You have more serious problems.

Unless you purchased it starting 3 years ago you got ripped off.