Yes you can not pay the estimates.  They are optional and don't get sent with your return so the IRS is not expecting them.  If you only have SS income it is not taxable and you don't need to file a return.  So you don't need any withholding taken out of your social security checks for next year.

Oh you should still pay the January 2018 Estimate.  That is based on all your 2017 income.  Why did you have Estimates for 2017?  Did you have a big tax due on your 2016 tax return?  Like did you have a big one time income increase like from a IRA withdrawal?

Thank you for your reply.  Unfortunately Soc Sec "benefits" will be taxable since they will be over the Soc Sec amount. We filled form W-4V to have 10% withheld next year. 2017 is last year I have income from an employer; that's why I asked if est. tax payments for 2018 were mandatory.  Thank you again.

No.  If you ONLY get SS it is not taxable.  Are you married?  Then yes if your spouse has income then Up to 85% of Social Security becomes taxable when all your other income plus 1/2 your social security, reaches:
Married Filing Jointly: $32,000
Single or head of household: $25,000
Married Filing Separately: 0

Here's a FAQ on Estimates
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