If you require to purge a buffer anywhere in a flow, use the Buffer Purge destination step.
This step allows you to purge any buffer in any flow without creating a new flow or extra steps just to purge the buffer after the flow does what is required.
NB: Please note that you are still able to purge a buffer before inserting, updating, upserting or deleting records. This step is to merely purge a buffer anywhere in a flow with only one step.
Illustrated below is how the step looks. Highlighted is a drop down list where you can select the buffer that you want to purge and then click on the Save button to save the step with the change.
The below image is an example if you want to purge multiple buffers at a specific time. If you want to purge it in a particular flow, you can remove the schedule trigger and reference it as a Sync Flow in the flow.