Nascar heat 4 keeps uninstalling while downloading.

Are you able to use the Nascar disc on another console?
This helps us to isolate the issue even more

Did you tried cleaning the disc?

When you say hard restart, do you mean power cycling the console?

1. Turn off your console by pressing the Xbox button on the front of the console for about 10 seconds, until it shuts down completely.
2. Unplug the console's power cable from the console and from the power outlet. Wait 5 minutes.
Important: Be sure to wait at least 5 minutes. This step resets the power supply.
3. Plug the console power cable back in.
4. Press the Xbox button on your console to turn it on.

Hi and thanks for reaching Microsoft Xbox gamer's community. My name is Josef.
I'm an Independent Advisor and a Microsoft Xbox user like you.

Hope you're doing great today Bozotheclown

Please answer the following questions:

Buddy, is this happening on Xbox console?
If yes, which one do you have?
Is this happening only with this game?
And which troubleshooting steps you have done so far to fix this issue?

I'll be waiting for your answers, greetings from another Microsoft user!

Ok I will tried that and I dont have any other console

Yes
Xbox one s
Nascar heat 4 and Forza motorsports 7 both disc
Hard restart
Delete local save
Put power on energy-saver
cancel the installation

I can advise you couple thing more to try

As you're not able to test with another console soon and if the issue persists, the discs may be damaged:

1. Factory reset your console but keeping games and apps

Open Settings > System > Console info > reset, then select keep my games and apps

2. Perform an offline update for your console. In that way Xbox system will be updated from scratch.
For this you need a USB and PC to format it and transfer files provided in the link below (with steps):

https://support.xbox.com/en-US/help/hardware-ne...

All your progress and purchases are attached to the console, so all that will remain
You need to re-enter your Microsoft account details, double check you have the credentials and everything.