Hi Manuela,
In order to prevent a session from appearing on the agenda widget on the event website, you will need to click into the session on the session list and set "display on agenda" to no.
If you want to prevent a session from appearing on the sessions widget in the registration process, you will need to click into the session on the session list and set "allow registration" to no.
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Julia Plymack
Senior Customer Success Manager
Cvent
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