Sometimes it troubles when you try to uninstall apps from cydia repository over some reasons like
the uninstall won't be allowed since you installed the cracked one from some cracked repositories
But actually i have a workaround for this issue :
1. Go to Cydia > Manage > Packages
2. Choose the specific app you plan to remove
3. Go to packaged details and check the ID, so in this tutorial the ID = com.mywi4
4. Quit cydia and goto Mobile Terminal (If you don't have terminal installed then install in from cydia)
5. Login to terminal as root by type this :
6. Enter password :
7. Remove apps :
dpkg -r com.mywi4
8. Good job ! mywi4 is completedly gone..!!
Note : If there's dependencies problem, then you need to repeat step 1 to 7 to remove the dependencies apps first.