Let us come together in the name of Jesus Christ, for there is power in His name. It is only through Jesus that we have access to God, and it is in His name that we pray for this situation.
Firstly, we must remember that God works in the hearts and minds of those who are open to Him. We pray that A will be receptive to the Holy Spirit's nudging and conviction. We stand in the gap for them:
Dear Lord, we bring A before You, asking that You soften their heart and transform their attitude. Replace the negativity with Your positive influence, granting them the wisdom to see situations from a new perspective. Fill them with Your grace to respond with kindness and patience. Help them understand the power of their words and actions, and guide them towards a life that reflects a better attitude, one that honors You.
And we must not give up hope: I am confident that he who began a good work in [A] will carry it on to completion until the day of Christ Jesus. (Philippians 1:6 WEB)
However, we must also address the latter part of the request. It is important to remember that God gives us free will, and He does not force change upon us. We cannot ask God to remove someone if they do not want to change. Instead, we should pray for conviction, for God to open their eyes, and for them to turn to Jesus. We cannot have a heart for salvation and not desire what is best for all. We pray now for their salvation, if they are unsaved:
Lord, if [A] does not know Jesus as their Savior, we pray that You would reveal Yourself to them. Open their eyes to see their need for salvation. Lord we need to remember: 'For God so loved the world, that he gave his only begotten Son, that whoever believes in him shall not perish, but have eternal life. For God didnโt send his Son into the world to judge the world, but that the world should be saved through him.' (John 3:16,17 WEB) and 'There is no other name under heaven given among men, whereby we must be saved.' (Acts 4:12 WEB).
Finally, let us examine our own hearts. We should not approach God with conditions, such as asking Him to remove someone if they do not change. Instead, we should pray for the salvation and transformation of all, regardless of their current state. We should ask Lord, is there anything in me that should not be there? Please reveal it to us Lord so we may repent. Remember WEB 3 John 1:2 - Beloved, I pray that you may prosper in all things and be healthy, even as your soul prospers.
Also, we should be regularly meeting with other believers for fellowship, edification, encouraging each other, discipleship, and sharing meals together. We are to do so more so the closer we get to the return of our Lord. (WEB Hebrews 10:23-25), (WEB Acts 2:42)