I appreciate your comment and attempt to help, but that still doesn't answer my question. I know how to find what you've described, but how do I delete, say, "PreCentral Search" or "Dictionary.com" as Just Type options? Again, swipe-to-delete doesn't work in this case.
I also wanted to know if it is possible to remove unwanted search engine from the Just Type preference list. Here is what I found :
1. using the Internalz program (thank JR for this wonderful program), you go to this thread in your Touchpad : /var/palm/data/universalsearchmgr/
2. you'll find there 2 folders :
a. in "searchplugins", you'll find "some" search engine that are used by Just Type.
b. in "assets", you'll find the icon for thoses search engine
3. erase the files that you don't want in you're Just Type preference panel and restart you're device.
4. you should have deleted the unwanted search engine
NOTA : this is what I tried and it worked for me. However, they were some search engine that comes from programs (and not from websites) that doesn't show in the folders named above. If you find something else, please let us know ! And forgive my english, it is not my primary langage