deno upgrade --version with whatever you supply fails with helpful message.
To reiterate, the above answers will not work anymore use
Specific version
deno upgrade 1.45.0
deno upgrade 1.46.0-rc.1
deno upgrade 9bc2dd29ad6ba334fd57a20114e367d3c04763d4
From testing the commit hash route is broken due to some reasons. Ah! The file is not available anymore, really weird in my case but in some cases a sec nightmare.
Using a multiplexer like dvm is a better alternative to manually upgrading, downgrading.