Add section on deleting objects in Flow

[exalate-issue-sync]

There are a few ways to delete objects in Flow that we should clarify for users:

• get Frames list -> check off -> Delete selected frames
  !image-2021-05-19-12-32-22-011.png|thumbnail!
• List Models -> check off -> Delete selected
  !image-2021-05-19-12-32-15-032.png|thumbnail!
• Run command in cell: deleteAll
  This can be added in the Flow section (before [Shutdown Down H2O|http://docs.h2o.ai/h2o/latest-stable/h2o-docs/flow.html#shutting-down-h2o])

[h2o-ops]

JIRA Issue Details

Jira Issue: PUBDEV-8158
Assignee: hannah.tillman
Reporter: Neema Mashayekhi
State: Resolved
Fix Version: 3.32.1.4
Attachments: Available (Count: 2)
Development PRs: Available

[h2o-ops]

Attachments From Jira

Attachment Name: image-2021-05-19-12-32-15-032.png
Attached By: Neema Mashayekhi
File Link:https://h2o-3-jira-github-migration.s3.amazonaws.com/PUBDEV-8158/image-2021-05-19-12-32-15-032.png

Attachment Name: image-2021-05-19-12-32-22-011.png
Attached By: Neema Mashayekhi
File Link:https://h2o-3-jira-github-migration.s3.amazonaws.com/PUBDEV-8158/image-2021-05-19-12-32-22-011.png

[h2o-ops]

Linked PRs from JIRA

#5506