Vodafone's former chief Sir Christopher Gent has given up his honorary post as life president of the group.
Mr Sarin took over as Vodafone chief in 2003
The move came as the mobile giant has been trying to quash rumours of a boardroom rift.
As news of Mr Gent's decision emerged, Vodafone chairman Lord McLaurin issued a statement dismissing claims he had tried to oust current chief Arun Sarin.
Lord McLaurin gave his full backing to Mr Sarin, saying he had read reports of a rift with "great concern".
"I want to make it clear that I and the Board are totally supportive of our chief executive ... as he takes the company forward in changing and challenging times," the statement added.
"Any other suggestion is completely untrue."
The statement followed media speculation that Lord McLaurin had been trying to get rid of Mr Sarin following a number of disappointing announcements from the firm.
Earlier this month Vodafone said it was in talks about selling its struggling Japanese phone business.
And last month it warned its assets were overvalued by as much as £28bn, as it faces slowing revenue growth. That news drove its shares to three year lows.
Recent reports have speculated about a boardroom rift between Vodafone's so-called old guard -consisting of Lord MacLaurin and Sir Christopher - and a new team of executives appointed by Mr Sarin.
Sir Christopher said he had decided to relinquish his honorary position - which has no executive or advisory responsibilities - following the rumours.
Any claims he had used his post to interfere in the running of the company were "without foundation", he added.