Umbraco database tends to grow quite quickly especially when
it's a high-traffic website. There are several thing you can do in
order to reduce its size.
Shrink database log file
First of all, try shrinking the database log. To do that, in SQL
Management tool, right click on the database, select Tasks ->
Shrink -> Files. In the Shrink File window, change file type to
Log and click on OK.
Tasks -> Shrink -> Database and click OK, if database is
large, this may take several minutes. In terms of reducing the
database size, this is probably the most effective way.
Empty Umbraco log table
Execute TRUNCATE umbracoLog to empty the database. TRUNCATE is
quicker than DELETE and will reset the counter back to 0.