Mortgage advice please??

Hi all, I have got two mortgages on two houses not through choice. I bought a house to extend and sell on but eventually moved into after loving the layout but couldn't get my other hose sold due to the market crash. Currently renting out but this is amusing me a dilemma and looking for advice.

On the house I stay in I have a mortgage of around £138000 which is a offset mortgage at 1.99% costing around £200 a month on interest.

On my other house which I rent out I have a mortgage of £158000 which costs me £657 a month on interest only and I am only able to achieve £625 a month on rental income.

I have shares that are worth over £100000 if I were to sell along with savings of around £20000. I could also take money from my existing mortgage of £138000 up £154000 allowing £16000 that could reduce my rental mortgage.

My question is, should I look to reduce my rental mortgage by selling shares which has capital gains implications, use my savings and take the extra money out on my existing mortgage which has a rate of 1.99% potentially saving me money or try and pay off some of each mortgage by using savings/share sales?

Really don't know what is the best route is to go down and would appreciate some expertise advice?

Thanks