CRM Plugin: Delete multiple records base on QueryExpression

Hi all,

I'm trying to create a plugin to delete some records base on a lookup field.

I'm now using QueryExpression and Filter to query those should be deleted, under the condition such as "lookup filed" Equals "certain GUID".  So, there will be multiple records retrieved as an EntityCollection.

I wanna know how can the program delete once by using the query result.

Btw, if there're not so many records, is it recommended to delete one by one with loop?  How can I take it into consideration.

Thanks,

Yvonne