For Slack integration navigate to Settings >> Integrations tab.
Connecting Slack & UpRaise
Click on Add to Slack & you will be navigated to authorize UpRaise access to your Slack details. The scope of this access will be visible on the authorize page. This is how the page will look like.
Once authorized you will be navigated back to the UpRaise settings page. On integration page, you should now see Slack integration in connected state which is why you find an option Disconnect Slack on this page.
Disconnecting Slack & UpRaise
When in connected state, Disconnect action against Slack integration is displayed (above image). Click on that button & connectivity between UpRaise and Slack will no longer exist.
In order to use Slack integration at the user level, it needs to be set up at the instance level. Managing Slack integration for more details.
When Slack is in the connected state, an additional column would appear under company directory >> users tab. This column would indicate whether a user is in UpRaise has his Slack account connected. Active Slack icon indicates that user is connected in Slack whereas the disabled state indicates Upraise was not able to find a Slack account with that user's email address.
User-level Slack connection
Click on these icons to connect/disconnect Slack accounts at the user level.
Few important points to note here -
At the time of Slack authorization, UpRaise automatically connects users in UpRaise with their respective Slack accounts by comparing email addresses
The underlying assumption is - that both UpRaise /Jira & Slack accounts are based on the same email address
Users whose email addresses in UpRaise/Jira do not match with any Slack account are left in the disconnected state
By clicking on the icon against each user, you will be able to check which email address is used for matching Upraise/Jira account to Slack account