This post demonstrates how to create a button that will drop down a cumulative vwap from the clicked bar forward.

Simply add a Cumulative VWAP to your chart with the Custom Duration set to "Cumulative From Date/Time (Anchored)".  Also setup the colors, bands, and Band Basis to your preference.  The actual date/time is not important at this point.

Now simply drag the VWAP line (blue in my chart) and drop it on any bar.  The VWAP will transform to start on that bar and build forward to present.  You can continue to drag and drop that VWAP line to any starting point.  You can also right-click on that line and Add Button.....and then edit that button to give it a purpose of "Activate Drawing Tool Preset".  This will add a button to your chart that will invoke a drawing tool that allows you to again click on the starting bar to drop down a new cumulative VWAP.

You may also simply Ctrl-drag/drop the VWAP line to another bar....this will leave the original VWAP in place and drop a new instance of VWAP on the target bar.

The following video demonstrates much of this (it is a bit dated on the VWAP preference window).

https://www.linnsoft.com/videos/cumulative-vwap