If the Compute Engine service account was deleted less than 30 days, you can recover it as per this
document. You would need to re-apply the IAM role
"Project Editor" on the account. If it is was deleted beyond the period, maybe creating a custom account would work.
I assume you are referring to the marketplace solution as per this
document. It seems that you can not specify a custom service account. To work around it, you may try using the gcloud command in
cloudshell as instructed in this
document. However, you would need to
create a custom service account and give it
IAM roles on the project. When executing the command, use this additional flag "--service-account=service account you created". If you are using an Editor role, it is a good idea to limit API scopes on the instance using --scopes flag also. Here is an
explanation about how they work together. Here is also a
reference on the gcloud command that might help.
If that seems complex, and if you are just testing the instance, maybe creating a new project under the Organization would be a good alternative. The default Compute Engine service account should be automatically created. I hope this helps.