Vba in powerpoint to clear a text box

Hello,

I'm developing a Powerpoint to work as an interactive "program" for an escape-room type activity. The user enters different account numbers into a text box (Command Button ActiveX Control) and depending on what is entered, a MsgBox appears, providing them with information. My question is... in VBA, how do I clear the textbox after the user clicks the OK button on the message box? Something like If OKonly Then textbox1.clear... but cannot get my code correct.

Post the code used to create the msgbox.