If you aren't using Poll feature you can delete the Poll folder and delete PollFeature.Business.dll, PollFeature.Data.dll, and PollFeature.UI.dll from the bin folder and you can delete the setup folder /Setup/applications/pollfeature-byChristianFredh
Same with Survey and WebStore, you can delete the folders, corresponding dlls and setup files.
Additionally, you can delete the sql scripts for dbs you are not using from under /Setup/applications/mojoportal-core/SchemaInstallScripts and from /SchemaUpgradeScripts. ie if you are using MSSQL, you can delete the ones for MySql, Pgsql, Firebird and sqlite.
You can also delete the SiteOffice folder.
Hope it helps,