How to delete a folder (if it is empty) from Inno Setup code?

Question

I always install a program (B = {app}) inside of the C:\A (C:\A\B). I need to know how to use the DelTree function to delete B folder and A folder (the A folder only if is empty).

This is my code to delete B folder:

DelTree(ExpandConstant('{app}'), True, True, True);

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I need this to rollback an installation of prerequisities, when the installation fails or is cancelled. So I cannot use UninstallDelete or InstallDelete sections.

Answer 1

Just use RemoveDir and ignore errors.

Deletes an existing empty directory. The return value is True if a new directory was successfully deleted, or False if an error occurred.

Use ExtractFileDir to resolve a path to the parent folder of the {app}.

RemoveDir(ExtractFileDir(ExpandConstant('{app}')));