Function for formatting a timespan with optional trailing zero
If your goal is to reduce returns, you could use a single string.Format call and not make use of additional arguments in certain cases:

// Changed removeZeroes to includeZeroes since it read kind of like a double negative.
string format = includeZeros ? "{0:d}d {1:d}h" : "{0:d}d";

// span.Hours will not get used if there's nowhere to put it in the format string:
return string.Format(format, span.Days, span.Hours);