Here, have a copy/paste tutorial:
Changing Your Blockland Profile Path (for Windows)
Right click on your Blockland shortcut and go to Properties. Click the Shortcut tab.
The target field will look something like this:
"C:\Program Files (x86)\Blockland\BlocklandLauncher.exe"
To change Blockland's directory, add the -profilePath "C:\Path to\folder" parameter to the end. The target should now look like this:
"C:\Program Files (x86)\Blockland\BlocklandLauncher.exe" -profilePath "C:\Path to\folder"
You can now launch the game using that shortcut and it will install the files to your new profile path.