Reading your question again.
Create a new database. Make a feature dataset in the projection you want to use for your Lat Long
Example WGS 84 or Web Mercator.
Right click on the feature dataset and import features. Select your UTM feature class and import it into the new feature dataset. ArcGIS will automatically re- project your data.
Be advised if you project it into a projection that is not appropriate for your location it will skew your data.