Problems deleting columns of the attribute table of a layer

I am not able to delete columns of the attribute table that I am not interested in. The program starts loading features instead of deleting them. Do you know how can I solve this and create a layer after all with maybe only 10 columns in the attribute table.

For example I create a layer of railway rail in Germany, which is huge, and after that i would love to only have columns like voltage, tracks, etc; deleting the other ones. Why am I having problems and how can I solve this?

Thanks for your help.

If you are using the Quick Query option, you can click the Show Query button to display the overpass code for the query instead of running it directly from the quick query screen. Alternately you can write your own overpass query from scratch in the Query tab.

Once this code is displayed in the query view, you can then expand the Advanced panel and type the keys you want in the text input fields next to the selection boxes for points lines etc. These should be comma separated. The columns full_id, osm_id and osm_type seem to be included whether you ask for them or not.