Cannot delete Atom Type and Master Terms

[shrmiao]

Describe the bug
Cannot remove atom type or master terms (can add and duplicate)

To Reproduce

1. Import species from LigParGen without "simplify atom types"
2. Try to manually delete duplicating Atom Types

Expected behaviour
To be able to remove redundant atom types (and master terms) if the selected atom type is not used in any existing species.

Operating System:

• OS: Linux
• OS version / flavour: IDAaaS