Delete it from the Application folder "Install macOS Catalina.app" ... empty the trash.
see: macOS Catalina - Technical Specifications - Apple Support
https://support.apple.com/kb/SP803?locale=en_US
You are so far behind in the macOS— that you will have to stair step your way up.
You will need at least OS X 10.11 El Capitan to move ahead
- Technical Specifications:
https://support.apple.com/kb/SP728
How to upgrade to OS X El Capitan - Apple Support
https://support.apple.com/en-us/HT206886
download direct:
http://updates-http.cdn-apple.com/2019/cert/061-41424-20191024-218af9ec-cf50-4516-9011-228c78eda3d2/InstallMacOSX.dmg
or High Sierra—
macOS 10.13 High Sierra - Technical Specifications:
https://support.apple.com/kb/SP765?locale=en_US
https://itunes.apple.com/us/app/macos-high-sierra/id1246284741?ls=1&mt=12
How to upgrade to macOS High Sierra
https://support.apple.com/en-us/HT208969
MacBook (Late 2009 or newer)
MacBook Pro (Mid 2010 or newer)
MacBook Air (Late 2010 or newer)
Mac mini (Mid 2010 or newer)
iMac (Late 2009 or newer)
Mac Pro (Mid 2010 or newer)
Once installed and all is working as expected— always recommende to have a current back up before you continue. Only in this way will you be able to fall back if something goes sideways.
Please note:
With the release of macOS 10.15 Catalina, applications will have to be 64-bit. App developers will issue updated apps if they want their apps to work on this newest macOS upgrade
32-bit app compatibility with macOS High Sierra 10.13 ... - Apple Support
https://support.apple.com/en-us/HT208436
Check Your Apps and Prepare for a 64-bit World
https://www.stclairsoft.com/Go64/index.html