how to clear Select options if value of another field is changed
I have a requirement that in selection screen there is a parameter input if some value is provided to this field, f4 help for another select option field will be populated with respect to the parameter input and i have designed like that, i have a problem that if the user changes the parameter value i want to clear the previously selected value in the select options
S1 ='f4 help dependin on INPUT1'
P1 = 'INPUT2'
S1='Old input must be changed'