Revision two. I was half asleep the first time & gave poor advice.
Looks like it's bent backwards from that photo, but that may depend on the camera lens & angle the picture was taken, so be certain before you make any adjustment.
Use a steel rule laid edgewise down the neck, or hold a string down at the 1st & 12th fret to judge.
Don't start before it's strung & in tune.
If it's been unstrung for a long time, string it, tune it & let it rest a week before you even start. Your early random attempts will not help this. You really should have strung it first & let it rest. As you've apparently dropped all the tension off the truss rod without it strung, you've made the job harder, so now you have to be patient.
Clockwise to pull it back, counter-clockwise to allow it to be pulled forwards by the string tension.
If all you have to adjust it is an Allen key*, you may need to keep alternately tuning & slackening at least the centre strings to give you room to work & also check how it's sitting.
That's not a fast job.
Once it gets anywhere close, leave it to rest a couple of days before continuing. If you have to drag it a long way, the neck movement will take from hours to a week to finally settle; you can make finer adjustments as it starts to come to an equilibrium.
Don't try to get it right all in one go, & make sure to leave it in tune between attempts.
If, even after a couple of weeks it still bends back with no tension at all on the truss rod [assuming a correct guess based on the photo] then you will have to take it to a luthier to be straightened.
*What you really need is a long-shaft screwdriver with interchangeable hex bits & a universal joint. Then you can do it without having to drop the string tension.