The problem is X This problem can be easily solved by doing Y
Therefore this problem can be easily solved
I am confused if this is Simplification (Which means the inference is Valid)
No. "Simplification" is typically use for the rule of conjunction elimination in propositional logic. This inference is not even propositional, it requires a predicate S(X,Y), "Y easily solves X", and goes like this S(X,Y) → ∃zS(X,z). This is valid, but not by conjunction elimination. It is called existential generalization.
In a way, it is similar in spirit: we are going from a more specific statement to a less specific one, as in simplification. Disjunction introduction and universal instantiation work that way too. Such inferences in logic are sometimes collectively called "weakening".