Once again, the error message is very helpful.
So, R says you that you can't give more than one argument to return, and it says so because you supplied na.rm=TRUE to the return, instead of the desired functions quantile and IQR.
Please go through the documentation of these functions. You're supposed to call like quantile(x = variable_of_interest, probs = probabilities_of_interest, na.rm = TRUE), and IQR(x = variable_of_interest, na.rm = TRUE) for each call.
An alternative will be to remove all the missing values a priori to avoid several na.rm's.