Speculative Generality

Signs and Symptoms

There is an unused class, method, field or parameter.

Reasons for the Problem

Sometimes code is created “just in case” to support anticipated future features that never get implemented. As a result, code becomes hard to understand and support.

Treatment

For removing unused abstract classes, try Collapse Hierarchy.

Unnecessary delegation of functionality to another class can be eliminated via Inline Class.
Unused methods? Use Inline Method to get rid of them.
Methods with unused parameters should be given a look with the help of Remove Parameter.
Unused fields can be simply deleted.

Payoff

Slimmer code.
Easier support.

When to Ignore

If you are working on a framework, it is eminently reasonable to create functionality not used in the framework itself, as long as the functionality is needed by the frameworks’s users.
Before deleting elements, make sure that they are not used in unit tests. This happens if tests need a way to get certain internal information from a class or perform special testing-related actions.