Answer
The proposed decay process conserves charge.
Work Step by Step
The $\Xi^-$ has charge $-1$
The $\pi^-$ has charge $-1$
The neutron $n$ has charge $0$
The $K^-$ has charge $-1$
The proton $p$ has charge $+1$
The left side of the proposed decay process has net charge $-1$ and the right side of the proposed decay process has net charge $-1$
Therefore, the proposed decay process conserves charge.
