Me despido del participante.

Because the verb here is despedirse, which means to say goodbye or to take leave. It is a pronominal verb, so it normally appears with a reflexive pronoun:

• me despido = I say goodbye
• te despides = you say goodbye
• se despide = he/she says goodbye

If you say just despido, that usually comes from the non-pronominal verb despedir, which often means to dismiss, to fire, or to send off depending on context.

So:

• Me despido del participante = I say goodbye to the participant.
• Despido al participante = I dismiss/fire/send off the participant.

That is a very important difference.

It is the present indicative, first person singular.

The full conjugation of despedirse in the present is:

• me despido
• te despides
• se despide
• nos despedimos
• se despiden

So me despido literally means I say goodbye or I am saying goodbye, depending on context.

Because despedirse is a stem-changing verb in the present tense. The e in the stem changes to i in most forms.

Examples:

• me despido
• te despides
• se despide
• nos despedimos ← no stem change here
• se despiden

This is similar to other Spanish verbs that change in the stem in some present-tense forms.

Because de + el contracts to del in Spanish.

So:

• de + el = del

That is why you say:

• Me despido del participante

not

• Me despido de el participante

This contraction is required whenever de is followed by the masculine singular article el, unless El is part of a proper name.

Because despedirse is commonly followed by de to mark the person or thing you are saying goodbye to.

Examples:

• Me despido de Ana.
• Nos despedimos del profesor.
• Se despidieron de sus amigos.

So in this sentence:

• del participante = of/from the participant, but in natural English we translate it as to the participant after say goodbye.

This is just the preposition Spanish uses with this verb.

No, not with the meaning I say goodbye to the participant.

With despedirse, you normally use de, not a:

• correct: Me despido del participante
• incorrect for this meaning: Me despido al participante

If you use a, you are probably mixing it up with the non-pronominal verb despedir a alguien, which can mean to dismiss someone or sometimes to see someone off.

Participante means participant. It is a common and perfectly normal word in both Latin America and Spain, especially in formal, academic, professional, workshop, event, or survey contexts.

For example:

• los participantes del curso
• una participante del taller
• el participante

It can refer to a person taking part in an activity, event, study, meeting, program, and so on.

The noun participante can refer to either a man or a woman. The form of the noun usually stays the same; the article and adjectives show gender if needed.

Examples:

• el participante
• la participante

So in your sentence, del participante means the person is being referred to as masculine, or masculine grammatical gender is being used.

Yes. The Spanish present tense often covers both ideas:

• I say goodbye to the participant
• I am saying goodbye to the participant

The exact English translation depends on context. Spanish does not have to choose between those two as strictly as English does.

Because object/reflexive pronouns like me, te, se, nos normally go before a conjugated verb.

So:

• Me despido = correct
• Despido me = incorrect

With infinitives, gerunds, and affirmative commands, pronouns can attach to the end, but not here because despido is a conjugated present-tense form.

You can change either the subject, the person being said goodbye to, or both.

Examples:

• Nos despedimos del participante. = We say goodbye to the participant.
• Me despido de los participantes. = I say goodbye to the participants.
• Nos despedimos de los participantes. = We say goodbye to the participants.

Notice:

• del = de + el
• de los does not contract

Both can express saying goodbye, but they are built differently.

• despedirse de alguien
• decir adiós a alguien

Examples:

• Me despido del participante.
• Le digo adiós al participante.

Both are possible, but despedirse de is very common and often feels a bit more standard or neutral as a verb for taking leave.

Yes, it sounds fairly neutral to formal, especially because of the noun participante. It would fit well in contexts like:

• presentations
• workshops
• meetings
• research studies
• formal events

In a casual everyday situation, you might more often hear something with a person’s name or a more personal noun, such as amigo, vecino, or compañero. But the grammar is completely normal either way.