How to close FVTool window using commands?

Within a script I can use commands to generate FVTool plots, edit them, and save the results...

fd = fdesign.highpass(60,70,60,1,2e4);
hFilt = design(fd,'equiripple');
hFV = fvtool(hFilt); % open FVTool
xlim([0,0.1]); % zoom in to show the transition
print(hFV,'filter_transition.png','-dpng','-r300'); % save results
close(hFV); % plot closed, but window still open
close all; % window still open
delete(findall(0)); % error message

...But I can't figure out how to close the entire FVTool GUI window afterwards using commands. Using close(hFV) closes only the current plot, but not the system window enclosing it. How can I close the system window containing the FVTool plots?

I am using Matlab R2015b. Thanks in advance.

[Doan Vo]

Have the same question, for 2022a. Any help will be appreciated! Thanks.

[Mark Walters]

Ditto