Hi Frank
You could use the "trac-admin" command to clean up your Trac instance.
For the an overview of the help :
trac-admin path/to/trac help
For the wiki part, you can combine "wiki list" and "wiki remove <page>" using something like (assuming it's on Linux):
trac-admin path/to/trac wiki list | cut -d ' ' -f1 | while read wikipage; do trac-admin path/to/trac wiki remove $wikipage; done
This will also remove Trac integrated help pages. You should be able to reinstall them with:
trac-admin path/to/trac wiki upgrade
For the tickets it seems there isn't any command to list them. As they are identified by numbers, you can just check the highest number and generate a list:
seq HIGHESTNUMBER | while read ticketnum; do trac-admin path/to/trac ticket remove $ticketnum; done
If some tickets have already been removed, you will probably have error messages.
As usual, before starting these destructive actions, please make a backup of your database and Trac instance !
Best regards