The phrase "dismount for" is grammatically correct and can be used in written English.
It means to get off of a horse, bicycle, or other mode of transportation. It can also be used figuratively to mean to stop or cease an activity. Here is an example sentence: I decided to dismount for a few minutes and stretch my legs during our bike ride.
According to the Times "the Russians had demanded that our troops dismount for a head count, & we had refused.
Western troops don't always refuse to dismount for a head count but rather because we dismount "only if the convoy contains more than 30 persons, exclusive of drivers.
Next came the uneven bars, the lone apparatus where Biles has shown glimpses of mortality, where she stuck a perfect dismount for a 14.800.
After being carefully prepared — with an aerodynamic tail cap — and attached to the jumbo jet over the weekend, it was set to dismount for a last ride, by land, to the Virginia annex of the Smithsonian National Air and Space Museum.
We do the classic, John Wayne-like dismount for the benefit of the tourists unloading from taxis at the Marriott.
As mounted infantry, the regiment rode into battle on their horses, but were expected to dismount for battle, and then fight on foot.
And when we dismounted for the simple daily picnic, we would come across wild flowers – wood anemones, hellebores, dog's-tooth violets – making themselves visible with shy persistence.
Dettori usually reserves his flying dismounts for Group winners, but was moved to perform his trademark celebration after the opening nursery handicap at Doncaster, such was the impression made on him and a packed house by Nemoralia, who, under top weight, turned what was supposed to be an ultra-competitive handicap into a procession.
Her two 12-pounder 8 cwt guns could be dismounted for service ashore.
On 7 September 1904, her 15-centimeter guns were dismounted for use in the Siege of Port Arthur.
Two additional 12-pounder 8 cwt guns could be dismounted for service ashore.
