Can you cancel the free character transfer after initiating it?

[Levíathan-aerie-peak (Levíathan)]

Unfortunately, no.

• You cannot cancel a migration in progress.
• Blizzard Customer Support cannot cancel a migration or speed up the migration process.

From:

Free Character Transfers Now Available For Some Realms

With the launch of Shadowlands, great numbers of players have left Azeroth for the afterlife, dramatically increasing player populations on every realm. For a small number of realms, demand has been overwhelming, and we’ve been working around the clock to address issues on those realms and make the game available to the maximum number of players. Today, we’ve enabled the Free Character Transfer service for players who have characters on high population realms that are experiencing consistent, e…