@gped Here's the method that i used. it works, but its a pain in the ***. For me it was worth it because they were bunch of texts from my ex :p
From https://discussions.apple.com/thread/4932383
A lot of people have had issues with removing SMS from spotlight search, especially deleted ones. This method should help.
1. Download iFunbox to browse your phone's contents.
2. After connecting device and running iFunbox, click on "Raw file system" in the left pane.
3. Navigate to private/var/mobile/library/spotlight/com.apple.mobilesms
4. Locate the file "smssearchindex.sqlite". Right click it and select "copy to pc" save it where you please.
5. IMPORTANT! MAKE A COPY OF THIS FILE ELSEWHERE IN CASE YOU SCREW UP! I AM NOT RESPONSIBLE IF YOU GO DELETING THE WRONG STUFF!!!
6. Download SQLite administrator.
7. Open the file you saved to your computer using SQLite admin (you may need to change the "files of type:" option to "any file" when opening in order to locate it).
8. In the left pane click "ZSPRECORD" then click the Edit Data tab.
9. There should be a drop down menu that says Filterfield. Click to bring up the options.
10. From here you can choose how you want to filter the SMS. If you want to delete everything from a single person , select ZTITLE. If you want to delete individual messages, select ZSUMMARY.
11. In the filter box just to the right of the the drop down menu, type in the name of the person, or the first part of the message to filter your messages.
12. Clicking any of the cells in the spreadsheet of the filtered messages and clicking the minus button (-) right above the drop down menu will delete the message from your spotlight search.
13. Protip: if you are deleting a ton of SMS from a single person, you can click a cell in the spreadsheet of filtered results then click the minus button like normal. Except, if you hold down the return key, you will rapidly delete everything in the filtered spreadsheet.
14. After you've made your adjustments, close SQLite admin. Now just drag and drop your new file back into the same folder using iFunbox and you should be good to go!!
If you found you've made a mistake just replace your new file with the backup file i told you to make earlier and you should be back to square one.