How do you relieve the tension of the tensioner on the belt to remove or install a serpentine belt?

I have searched.
On the Mustang, there is a 1/2" square to engage with a breaker bar.

Maybe I am missing it, but where and how do you engage this tensioner?

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06 CRD LIMITED- Factory Belly Armor, Hooks.
EHM, MagnaFlow SS Cat Back, FS-2500, HDS 001 TStat, Some Gauges, PML Trans Pan, PML Diff Cover, Marinco Mod, FIA Blanket, Cooper Discoverer ATR 225/75, CTS 245/70, Front-JBA 2.25" C/Os, Rear-OME HD, JBA UCA, SS Brake Lines.

I use a closed end wrench and then put another one on it to get more leverage. I can't remember the size off the top of my head. Pretty sure it's metric

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2005 Crd Silver Limited- arps, rockers, 7v etechno's, egr deleted, v6 airbox, metal cac's. Yeti's stage 2 tune. Euro TC, Ram tcm, pml transmission pan, facet lift pump

Put a wrench on the bolt head of the tensioner pulley.

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U.S. Army Retired

Thanks for the instruction. Much appreciated.

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06 CRD LIMITED- Factory Belly Armor, Hooks.
EHM, MagnaFlow SS Cat Back, FS-2500, HDS 001 TStat, Some Gauges, PML Trans Pan, PML Diff Cover, Marinco Mod, FIA Blanket, Cooper Discoverer ATR 225/75, CTS 245/70, Front-JBA 2.25" C/Os, Rear-OME HD, JBA UCA, SS Brake Lines.