Start - Programs - Microsoft SQL Server - Enterprise Manager
Expand the folders untill you see the database-folder.
Rightclick your ePO_DATABASE and choose Properties
Goto the Options-tab, under Recovery you can choose the recovery-model, i guess this is set to FULL instead of SIMPLE
At this tab, you can also set the AutoShrink-checkmark.
Under the DataFiles-tab you can set the AutoGrow-value (grow by 10%)
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If you want to manually shrink the database or logfile:
Rightclick your ePO_DATABASE, choose All Tasks - Shrink Database
Click the button Files... on the bottom of the window to shrink the files you want. Also you can see how much free space there is in each.
Another tip:
Rightclick your ePO_DATABASE, choose View - Taskpad
Now, when you leftclick the ePO_DATABASE you can quickly see some interesting stugff in the right-window!