Using his sharp ear to guide himself, the little cat walked gently across the unstable roof of the inn to the window where the conversation was closer. Even with the window closed, it was clearly the refined voice of the Marquis's right hand. He was commanding two rough men, probably two quarrelsome mercenaries, to engage the noble soldier in a street fight, so they could later accuse him of starting such fight and ... Oh no! another cat is in the roof, and is approaching hostile!
Clare opened her eyes. She was in the ground floor of the inn, pretending to be a simple customer – I have to dismiss my poor familiar before the cats start a fight and alert the men that someone could be listening to them – but she can't even see her familiar from there.
Some effects, spells and even some magic objects can be dismissed using an Action, a Bonus Action or other. But which range and requirements does the Dismiss action have?
Lots of them (Dragon Wings, Disguise Self and others) have a range of 'Self', so the range of the Dismiss action doesn't seem to be a problem. But can you dismiss them being Prone, Restrained, Grappled or when you are trying to be discrete? Does the Dismiss Action have Verbal, Somatic or Material Components?
Others, like Find Familiar or Mage Armor, create an effect that can be very far before ending. Do you have to see the effect to dismiss them? Is there any limit on the range?
If the effect was created by a magic item by itself (not merely giving you the ability to cast a spell), like Instant Fortress, do you have to be in possession of, touching, or near the magic item to dismiss it?
Extra: Is putting a familiar into a dimensional pocket is comparable with the Dismiss action?