[InnoSetup] How To Proceed UnInstall Upon Question

[some1uk03]

Hello,

Can someone help me create a messagebox that will ask the user a question.

If Yes then Delete files if No skip.

Currently i have the following: But the messagebox never shows up..
I think because i dont know how to call this from the UnInstallDelete section.

[Code]
  // Ask the user a Yes/No question
begin
  if MsgBox('Would you like to keep your Settings?', mbConfirmation, MB_YESNO) = IDNO then
  begin
        // Delete all files and directories
        // but leave the directory itself
        DelTree('{userappdata}\MySoft', True, True, True);
 
  end;
 end.