One way:

You can unprotect your worksheet in the macro, then protect it again:

   Public Sub DelRows()
       Const sPWORD As String = "drowssap"
       Dim c As Range
       Dim strfind As String
       
       strfind = InputBox("enter value to find and delete")
       
       With Worksheets(1)
           .Unprotect Password:=sPWORD
           With .Range("A:A")
               Do
                   Set c = .Find( _
                           What:=strfind, _
                           LookIn:=xlValues, _
                           LookAt:=xlPart, _
                           MatchCase:=False)
                   If c Is Nothing Then Exit Do
                   c.EntireRow.Delete
               Loop
           End With
           .Protect Password:=sPWORD
       End With
   End Sub