100%? Hell no. Until something's hanging off on a stalk, it could go either way. They wont drop pollen yet anyhows, so unless you really need the space I would wait and see if they start to dangle, or grow a pistil.
Conversely, they are a little on the big side, and generally males do show a lot earlier...
If it doesnt hurt to wait see, dont go killing any just yet.
"if your growing in a room and want to sex them turn your light to 24hrs for about a week. them put them outside for a couple days or in the dark for a few 12hr incremants. this will cause them to flower immediatley showing sex. then just put them back under the light"
I really dont think messing with the plants like this is a good idea. Not only will it NOT happen immediately, IME messing with hormones in this way can sometimes seriously stunt growth. Either way it takes time for the plant to switch from one mode to another...this depends on strain, but it could be anywhere from a week to a month to switch forwards and backwards like this.
There is another technique you could try [if you wished to clarify sex earlier], which is detailed somewhere on here more clearly, but it is essentially to use a black bag to keep a single branch in darkness, for anywhere between 12 and 24 hours a day, depending on what stage youre at; this allows hormones to build up locally causing a single branch to flower earlier than the rest of the plant, which minimises the time and problems you might encounter doing unnatural things to the whole plant; all the while the rest of the plant enjoys and makes the most of its valuable light time, without interruption. The sex of flowered branch will be the sex of the plant.
IMO it isnt necessary to speed things up this time, as if some are starting to show the others wont be far behind. But I wouldnt go messing them up next time or even bothering to interrupt normal growth when its far easier to flower and reveg a single branch. [If you really have to]. GETRIPPED try this next time too, your plants will grow and finish a lot quicker, I promise!
gd luck getting females anyhow...