solved this by the following PageTSConfig:
[!backend.user.isAdmin]
mod.SHARED.colPos_list = 0,2
mod.web_layout.hideRestrictedCols = 1
[end]
Explanation: if user is not an admin only columns 0 and 2 are allowed to him. "hideRestrictedCols" finally removes a "restriction note" in the column by not showing this column.