Hi @Vinia_Marciano! ODK Central does not currently (as of v1.0) have an option to remove group names from the column headers in the submission CSV download.
What software are you using to manage or analyze your data? Could you say more about what would be useful about being able to remove group names? Is it to make the column headers more easily readable, or does the software you're using have limits related to the length of column headers? (For example, I think the maximum length of a variable name in Stata is 32 characters.)
You can use ODK Briefcase to remove group names, but like you said, right now the SubmissionDate column will be empty when you use Briefcase to pull from Central. Right now there's not a simple way to both remove group names and download submission dates. You could use Briefcase to remove group names, but you'd have to obtain submission dates another way and merge the two data sources using the submission instance ID.