When deleting a resource from your resource list page on Acho Studio, you will lose access to all the data tables within the resource.
When deleting a project, you are essentially closing all the tabs in this project. No data will be lost. You will however lose the actions, work logs, and annotations in each table.
When deleting a tab, you are essentially closing the tables in your project for more processing. The underlying tables including the ones you have joined, merged from another tab will be closed. All the actions that you have applied on this tab's table will be gone as well along with the work logs, comments, and annotations that have one resided in this tab.
Once deleted, these tables will not be retrieved back. The easiest way to get them back is to re-import the tables from your resources and re-apply all the actions you did.
Notice that if your table is set up Data Sync, remember to turn off it before deleting the table.