Check what still requires it
Review the dependency lists of the mod releases remaining in your pack. If any requires Placebo, removing the library will prevent a supported launch. A library can still be needed after one content mod is removed because another mod uses the same dependency.
Back up before simplifying
Save the instance and world first, then perform removal in a copy. Removing a content mod is a separate decision from removing its library: gameplay blocks, items or saved data may depend on the content mod even though Placebo itself does not add visible content.
Verify and retain a recovery path
Launch the test instance and read any missing-dependency message. Restore the required library if a remaining mod asks for it. Keep the previous working version set until you have tested the pack and world sufficiently to decide whether the simplified setup meets your needs.