Replace function and its derivatives by zero


If I try to replace the function u0 and its derivatives by zero in the following examplary expression

expr = t HeavisideTheta[0.174 +φ] - 1651.2 u0[t, φ] + 3293.841 t Derivative[0, 1][u0][t, φ]; expr/.u0->(0&) (*0. + t HeavisideTheta[0.174 + φ]*) 

Mathematica gives an output 0.+....

My question: How can I avoid this zero part 0.+ in the output(without using Chop) ? Thanks!