I don't think it's possible to delete individual entries, but you could filter them so you don't see them (the entry still exists but isn't displayed).
From the log select one of the entries and right click, select filter, type *eicar* in the exclude window and select 'Show only defined lines (hide the rest)'. You can remove the filter and you will be able to see them again.
When/if you want to delete the entries later it should get rid of the filtered items, but I believe the filter would still apply so if you do any testing you would not see the results in the log without switching off the filter.
HTH David