In latest JMeter there are irrelevant plugins in Plugins Manager (start with jmeter - ) as jmeter - JDBC Support
It display JMeter components which are part of JMeter and can't be uninstalled,
Manager UI allow to uninstalled and if clicking Apply Changes and Restart JMeter
it seems to have no real effect, but it's still very confusing.
It seems like a bug, but is it Plugin manager issue or JMeter? is there some purpose for displaying JMeter core features as plugins? can it be removed?