Presumeably you still want a trellis there. What's the possibility of building another next to/near to the old one and tie the vine to it. You could then cut away the old trellis without affecting the plant.

By the way, what's a YTT?

A lovely colour for sure.
chas

Wow! It's very beautiful. What is it?

Petria volubilis, 'Sandpaper vine'. Beautiful intense blue but can be a large and destructive vine if the support is not adequate. I had a picture of mine I think I posted a year or so ago but seems I lost it during the last computer crash. The leaves are quite tough and rough to the feel hence the name, sand-paper vine. Flowers in summer - mine's about to - unusual Gary for it to flower in the (Florida) winter!
B.

PS. I've cut mine right back - to just a couple of feet above ground level - and it still roars back strongly the next year, in fact you can almost watch it grow. So if it's causing difficulty with the trellis, why not just cut it back after it finishes flowering, rebuild or strengthen the trellis and let it grow back.
B.

hi
Should have made myself clearer lol YTT stands for Yesterday today and tomorrow common name for the shrub on the left because the flowers start dark purple fade to lavender then to white , The latin name is Brunfelsiia and I believe this is gradiflora rather than pauciflora but won't argue the point lol they are soo common here I forget that there are many names and types .
The Queens wreath (vine > is Petra volubilis though I think this is racemosa due to differences in the flowers
i'm not sure what regulates flowering but usually the grand show is in spring and then again in fall but never in winter. But this year ??? i blame it on global warming?? lol
Anyway Out of the pic is the main trunk which has emtwined onto the trellis so would have to cut it to the ground to remove it.. Actually the trellis is being supported by the vine as its only in the groung on one side.lol Here is a pic of the one on the opposite side of the area which had the same problem BUT was able to remove most of it. I'm attempting a "weeping form " standard but still relies on the property fence for support as the trunk is not strong enough Thanks for the help gary

I also have a couple of Brunsfelsias (yesterday, today and tomorrow). Mine, here in Aus. are traded as B. latifolia. Looks exactly like yours, at least the flowers do, they fade to a pale white by about the third day.

B.

Hi
There's quite a family of the Brunfelsia but very closely related .Main difference is size some remain under 3 feet while this one is well over 8 which is why I call it gradiflora.
Another difference is flowering period this one flowers exclusively in winter while others flower in summer .
Another striking difference is aroma some have an incredibly sweet,almost gardenia fragrance while mine has none I think there are also some hybrids to confuse the matter even more lol. My only complaint about them is they are water hogs least bit of dry and they wilt
As to the Petrea it grows very slowly for me .The reason I'm reluctant to do a severe prune . Was hoping they would "trunk " and become self supporting. Still my favoritre vine as it's NEVER once tried to eat the house !! lol gary

Many years ago we had a "shrub-tree?" called Pacific Blue, and because of the colour I wonder If they are related?
chas

Build a trellis next to the one that's collapsing.

Then tie the vine to the new support and hack out the rotting old one.

Some years ago I bought a Bruns. dwarf - suppose to not exceed 1.5 metres and flower as well as the larger variety. It grew to around 4 metres and never flowered! So I eradicated it. I also have a variegated variety, I no longer have the label but it's called b. 'Border Beauty'. Slow growing but lovely foliage.
B.