Amendment not withdrawn

**Describe the bug** When the creator of an amendment in collaborative text removes it the amendment can still be seen

**To Reproduce** : create an amendment

**Expected behavior** I expect a message that confirms that the ammendment has been removed and not to find on the ammendment list

**Screenshots** none

**Stacktrace** I don't know what an error stracktrace is.

**Extra data (please complete the following information):**

- Device: Desktop]

- Device OS:Ubuntu

- Browser: Firefox

- Decidim Version: 0.28 (i think)

- Decidim installation: iapolitics.network