To clear app data:
Go to System settings -> Apps -> Xodo -> Storage -> Clear data.
This following app content will be cleared when clearing the Xodo app data:
All preferences, i.e. anything in the app setting, any colors you added to your color picker, any menu item you've modified etc, will all disappear.
2. Recent and favorite list
These two lists will be cleared.
3. All folders/files stored in Android/data/com.xodo.pdf.reader/ will also be deleted.