Archive/Delete/ Manual Delete completed/Cancel Process

Manually deleting instances can be a first aid activity, but make sure to modify the model to consume less memory. Data management settings will not help here.

A lot of questions emerge more than answers.  How big is this process per instance?  How many times does this process run?  How long does it stay active?  Is there any way to split it?  Does it do queries?  Maybe you could get by with fewer fields being queried?  Does it perform many alterations to the data?  Those multiple alterations could be condensed into a single script task so you're not saving so many versions of the same data.

You could also consider archiving sooner, such as 1 day.  However, that's going to make chasing down bugs harder.  Your O&M team might not thank you, or they might.  That's the cost of archiving soon.  Ideally you'd do everything you can to make them as rare and small and short-lived as practicable and then archive according to best balance of general performance and ability to debug.

Following best practices would help - 

1. Archive/delete any unnecessary processes in the environment as soon as possible.

2. Revisit Data Management setting and configure process models appropriately

3. Analyze health check report to identify highest resource consumption.

4. Remove unused objects.