Can I tell an agent not to upgrade?

tldr Short question - our agent keeps failing on upgrade.  Is there a way I can tell it to not upgrade?

Long question -

We have a build agent that recently did the following:

It exits/stops the service so that it can upgrade.
As part of the many many file operations, it deletes TeamCityAgentService-windows-x86-32.exe (the service)
It then tries to copy a new TeamCityAgentService-windows-x86-32.exe from the update folder to the current folder.  At this point, it gets an access denied error:

WARN - buildServer.agent.LauncherUtil - java.io.IOException: Failed to copy C:\TeamCity\buildAgent\update\launcher\bin\TeamCityAgentService-windows-x86-32.exe to C:\TeamCity\buildAgent\launcher\bin\TeamCityAgentService-windows-x86-32.exe. Access is denied

This is mere moments (70 milliseconds) after the delete operation.

It realizes there's a problem and tries to restore from the backup folder.  Same problem though - access denied to the non-existent exe.

What could be the areas to investigate here, why is it unable to write the new exe even though (I checked) it deleted successfully?

Just to clarify - I've tried reinstalling the agent several times, and having it run as system account or an account with admin rights.

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I'm interested in simply disabling the agent.    This may be frowned upon but still would be nice to know if this can be done.