The apps are very suitable to view and share files on the go. Also, you can upload files (e.g. photos from your smartphone camera) as well as delete and move documents. Since there is only little space available on mobile devices as opposed to PCs, data are not automatically synchronized with the mobile apps. Instead, they are downloaded when you open the files manually. Here are the manuals for the android app and the iOS app.
The sciebo desktop app is an application for synchronizing the data in your sciebo directory with one or several local directories on you computer. The client works in the background and synchronizes your data automatically. So, if you or someone else modifies data in a shared folder, all modifications will be synchronized by uploading and downloading the modified data. Here is the manual for the desktop client.
The calendar is available only for ownCloud's free community version. Sciebo, however, is based on the Enterprise Edition which focuses on stability instead of groupware functions. For this reason, we can not offer the feature at the moment.
The sciebo desktop client is probably still active which is indicated by the sciebo icon in your task bar. Go to the client menu via the tasks bar and select "quit". Afterwards you should be able to delete the software.