if you create a button then unprotect all cells you want to clear then add a macros that when button presses all unprotected cells will clear --- If this will work for you use this macros
Code:
Option Explicit
Sub Button1_Click()
Dim rClear As Range
Dim rCl As Range
For Each rCl In ActiveSheet.UsedRange
If Not rCl.Locked = True Then
If rClear Is Nothing Then
Set rClear = rCl
Else: Set rClear = Union(rCl, rClear)
End If
End If
Next rCl
rClear.ClearContents
End Sub