[otrs] How to remove individual postings (not tickets)?

Hi, I'm sure this has already been asked in the past but I don't seem able to find any appropriate postings: How can I remove individual mails/postings (/not/ complete tickets!) in OTRS tickets? Background is, that due to technical problems I have several tickets with dozens of intermixed duplicate entries which makes these tickets almost unreadable and unusable. I'd like to remove the duplicate entries from these tickets. I don't care if this is done through the webgui or directly in the database. (But I have never dealt with the OTRS database directly so far) I'm using OTRS 3.2.9 on CentOS 5 with MySQL. Thanks in advance Frank