Clearing a Range of Cells defined by a Variable Range

Hi,

So my spreadsheet currently uses the variable "RowVal" which searches a column till it finds a selected value from a checkbox in a user form.

It works off a loop:

RowVal = 1
Do Until Range("Proposal_Projects!C4").Cells(RowVal, 1) = cbxProjectSelection
RowVal = RowVal + 1
Loop

What I am trying to do is to create a sub routine that clears all the cells within the row as well as 8 rows below it from which the "cbxProjectSelection" is found (Basically the RowVal). Issue is that most advice online suggests you use specific ranges (i.e A10:C25). Issue with this is that the range I wish to clear is variable depending on what the user wishes to clear. How can I clear cells based off a variable range?

Many Thanks,