Several notes:
Make sure you first get a list of all installed versions. I actually had the version I wanted to downgrade to already installed, but ended up uninstalling that as well. To see the list of all your versions do:
sudo gem list cocoapods
Then when you want to delete a version, specify that version.
sudo gem uninstall cocoapods -v 1.6.2
You could remove the version specifier -v 1.6.2 and that would delete all versions:
You may try all this and still see that the Cocoapods you expected is still installed. If that's the case then it might be because Cocoaposa is stored in a different directory.
sudo gem uninstall -n /usr/local/bin cocoapods -v 1.6.2
Then you will have to also install it in a different directory, otherwise you may get an error saying You don't have write permissions for the /usr/bin directory
sudo gem install -n /usr/local/bin cocoapods -v 1.6.1
To check which version is your default do:
pod --version
For more on the directory problem see here
If you need to install an older version (for example 0.25):
pod _0.25.0_ install
Note that your pod specs will remain, and are located at ~/.cocoapods/ . This directory may also need to be removed if you want a completely fresh install.
They can be removed using pod spec remove SPEC_NAME then pod setup
It may help to do pod spec remove master then pod setup
PROMPT> gem uninstall cocoapods
Select gem to uninstall:
1. cocoapods-0.32.1
2. cocoapods-0.33.1
3. cocoapods-0.36.0.beta.2
4. cocoapods-0.38.2
5. cocoapods-0.39.0
6. cocoapods-1.0.0
7. All versions
> 6
Successfully uninstalled cocoapods-1.0.0
PROMPT> gem install cocoapods -v 0.39.0
Successfully installed cocoapods-0.39.0
Parsing documentation for cocoapods-0.39.0
Done installing documentation for cocoapods after 1 seconds
1 gem installed
PROMPT> pod --version
0.39.0
PROMPT>
Actually, you don't need to downgrade – if you need to use older version in some projects, just specify the version that you need to use after pod command.
pod _0.37.2_ setup
Source: Stackoverflow.com