The Delete button in the TSA dialog should be disabled when no entry is selected. The dialog is found in Tools - Options - Security - TSAs
Created attachment 132331 [details] Time Stamp Authority dialog, delete button active with focus Confirmed.
Sabin Frandes committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/core/commit/?id=2b74f20c67bc23f3321d8d9425300d363646f594 tdf#106945 TSA Dialog: Disable delete button It will be available in 6.0.0. The patch should be included in the daily builds available at http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: http://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.