Are you sure that you correctly understand the meaning and scope of the document that has been proposed to you?
It is generally hard to try, after you have signed something, to undo the effect of a written statement you have signed, and much better and often easier not to sign it at all.
If you are under some kind of pressure to provide a document of the kind proposed, then it would be advisable first to try to have a dialogue with your supervisor or other person proposing it, to try to understand better just what s/he thinks it should suitably cover or contain. If you have taken part in an ancillary way in work that is mainly being done by others, and the circumstances are that you would not yourself think it fair for you to claim co-authorship in their publication, then in principle I see no harm in making a statement of the kind requested, so long as it is limited to that kind of involvement and that particular activity.
If on the other hand the supervisor turns out to be expecting you to make a disclaimer for work in which you have taken a part important enough for you to claim authorship or co-authorship, then you need to consider saying so, and claiming that authorship or co-authorship. There you have a potential dispute on your hands and you need to take advice beyond what is available in this forum.
If in addition the supervisor is really expecting you to make that kind of a disclaimer for work on which your part is really that of an innventor or coinventor, then the supervisor would be making a proposal which is actually illegal in India as in practically all other countries, and the people who wrongfully apply for a patent as a result of it would be at risk, if discovered, of losing the rights and of subjecting themselves to other legal risks also.
But in my experience there can indeed be situations in which a person P has had a (definite but slight) degree of involvement with a piece of work and its investigators A, B, &c, but not so much that a co-authorship is warranted for P in the resulting publication by A, B... . P's part may be worth a collegial acknowledgement but no more. Examples of such involvement can be those that go no further than generally useful conversation, or routine ancillary assistance.
If your department has a policy of clarifying the non-authorship of people in that ancillary position, and is not just aiming something specially at you, then I see no injustice or harm in your agreeing to take part in that precaution, just so long as you think carefully and take care about the breadth of any statement to which you may consider putting your name.
It may be useful for you to think through (1) which parts of your activities are those for which you definitely feel entitled to be an author or co-author in a resulting publication, and whether there are (2) activities that you have been involved with in an ancillary way, or parts you have taken in the work of others, for which you would not justly make such a claim.
If there is anything in category (2), then it seems to me that it would be reasonable and harmless for you to acknowledge it, as well as reasonable for the main investigators to ask for such an acknowledgement, to prevent disputes arising later. If there is anything in category (2) on which you feel prepared to give such an acknowledgement, then naturally the relevant description of the work of others to which your acknowledgement applies should be written in carefully limited terms, so that there is no risk of its effect 'spilling over' onto some activity or topic more important to you.
If you feel that you have not taken part in anything in category (2), i.e. that you have had no ancillary involvements that are too slight for you to claim to be a co-author, then your reply to your supervisor can simply be, that there is no work or activity in that category to which his proposed document would properly apply.
For your activities in category (1), the boot is entirely on the other foot. You should be prepared to state what your activities have been, and make positive claim of your activities and entitlement to be an author or co-author of any resulting publication, and you ought to be prepared to describe what those topics or activities have been. If, as it might seem, it is a policy in your department for ancillary helpers to be asked to disclaim being a co-author, then you should also consider making just that same kind of request in respect of any others who you are aware to have had an ancillary involvement in your own work that is so peripheral that they should not in justice seek to be named as author or co-author on the strength of it.