Function to remove covariates from a given variable's equation in the function string text
removeCovVar(fitobject, varName, covariate, categorical = FALSE, isHS = FALSE)an nlmixr 'fit' object
a string giving the variable name to which covariate needs to be added
a string giving the covariate name; must be present in the data used for 'fit'
a boolean to represent if the covariate to be added is categorical
a boolean to represent if the covariate to be added is hockey-stick normalized
returns a list containing the updated model and the parameter names for the covariates added