There's no proper uninstall tool for Office on Mac. To completely uninstall Office for Mac, follow these official instructions:
If you're not ready/able to upgrade to macOS Catalina, you can hide the update from Software Update.
Note that because of sudo, you'll need to be an admin on your Mac.
Open Terminal and enter the following command:
sudo softwareupdate --ignore "macOS Catalina"
Enter your password when prompted.
When you are ready to update, you can un-hide Catalina the same way:
sudo softwareupdate --reset-ignored
If you want to set the Dock size in macOS to a specific value, you can use the Terminal to do so:
defaults write com.apple.dock tilesize -int 32; killall Dock
This will set the icon size to 32px, and then restart Dock. Note that if you replace "write" with "read", you can get the current value of the Dock size.