Earnings reduced - my mortgage is 6 x earnings

Hello everyone, this is my first post and I've had a quick look to check this subject hasn't been discussed before. Any advice would be greatly appreciated.

I am currently maintaining my mortgage payments BUT as it says in the thread title my mortgage is 6 times my current earnings having taken a significant pay cut 12 months ago.

I want to reduce my costs a little so would like to move property (buying) but something a little cheaper with lower maintenance costs.

I am wondering if I was to approach my current lender and explain the scenario then suggest I'd like to reduce my mortgage (but not significantly - to say 5x my earnings) to move

a) could they actually withdraw my current mortgage or force me to relinquish/ it in some way and
b) how otherwise might they view such an application.

As I see it on the one hand I am trying to be responsible and reduce my costs and actually lower my mortgage accordingly but on the other they are likely to see it negatively from a risk point of view - I wonder is there any typical conditions or responses to such a situation.

I might add my mortgage is/would be 70%

Any advice is appreciated.

Thanks in advance.